@article{ruan_akutsu_yang_zayan_dou_liu_bose_brody_lamb_li_2023, title={Hydrogenation of bio-oil-derived oxygenates at ambient conditions via a two-step redox cycle}, volume={4}, ISSN={["2666-3864"]}, url={https://doi.org/10.1016/j.xcrp.2023.101506}, DOI={10.1016/j.xcrp.2023.101506}, abstractNote={A key challenge in upgrading bio-oils to renewable fuels and chemicals resides in developing effective and versatile hydrogenation systems. Herein, a two-step solar thermochemical hydrogenation process that sources hydrogen directly from water and concentrated solar radiation for furfural upgrading is reported. High catalytic performance is achieved at room temperature and atmospheric pressure, with up to two-orders-of-magnitude-higher hydrogen utilization efficiency compared with state-of-the-art catalytic hydrogenation. A metal or reduced metal oxide provides the active sites for furfural adsorption and water dissociation. The in situ-generated reactive hydrogen atoms hydrogenate furfural and biomass-derived oxygenates, eliminating the barriers to hydrogen dissolution and the subsequent dissociation at the catalyst surface. Hydrogenation selectivity can be conveniently mediated by solvents with different polarity and metal/reduced metal oxide catalysts with varying oxophilicity. This work provides an efficient and versatile strategy for bio-oil upgrading and a promising pathway for renewable energy storage.}, number={7}, journal={CELL REPORTS PHYSICAL SCIENCE}, author={Ruan, Chongyan and Akutsu, Ryota and Yang, Kunran and Zayan, Noha M. and Dou, Jian and Liu, Junchen and Bose, Arnab and Brody, Leo and Lamb, H. Henry and Li, Fanxing}, year={2023}, month={Jul} }
 @article{thompson_lamb_2023, title={Palladium-Rhenium Catalysts for Selective Hydrogenation of Furfural: Influence of Catalyst Preparation on Structure and Performance}, volume={13}, ISSN={["2073-4344"]}, DOI={10.3390/catal13091239}, abstractNote={PdRe/Al2O3 catalysts are highly selective for hydrogenation of furfural to furfuryl alcohol (FAL). Moreover, the synergy between the metals can result in greater specific activity (higher turnover frequency, TOF) than exhibited by either metal alone. Bimetallic catalyst structure depends strongly on the metal precursors employed and their addition sequence to the support. In this work, PdRe/Al2O3 catalysts were prepared by: (i) co-impregnation (CI) and sequential impregnation (SI) of γ-Al2O3 using HReO4 and Pd(NO3)2, (ii) SI using NH4ReO4 and [Pd(NH3)4(NO3)2], (iii) HReO4 addition to a reduced and passivated Pd/Al2O3 catalyst, and (iv) impregnation with the double complex salt (DCS), [Pd(NH3)4(ReO4)2]. Raman spectroscopy and temperature-programmed reduction (TPR) evidence larger supported PdO crystallites in catalysts prepared using Pd(NO3)2 than [Pd(NH3)4(NO3)2]. Surface [ReO4]− species detected by Raman exhibit TPR peak temperatures from ranging 85 to 260 °C (versus 375 °C for Re/Al2O3). After H2 reduction at 400 °C, the catalysts were characterized by chemisorption, temperature-programmed hydride decomposition (TPHD), CO diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and scanning transmission electron microscopy (STEM) with energy-dispersive x-ray (EDX) spectroscopy. The CI catalyst containing supported Pd–Re alloy crystallites had a TOF similar to Pd/Al2O3 but higher (61%) FAL selectivity. In contrast, catalysts prepared by methods (ii–iv) containing supported Pd-Re nanoparticles exhibit higher TOFs and up to 78% FAL selectivity.}, number={9}, journal={CATALYSTS}, author={Thompson, Simon T. and Lamb, H. Henry}, year={2023}, month={Sep} }
 @article{mccaig_lamb_2022, title={Ni-H-Beta Catalysts for Ethylene Oligomerization: Impact of Parent Cation on Ni Loading, Speciation, and Siting}, volume={12}, ISSN={["2073-4344"]}, DOI={10.3390/catal12080824}, abstractNote={Ni-H-Beta catalysts for ethylene oligomerization (EO) were prepared by ion exchange of NH4-Beta and H-Beta zeolites with aqueous Ni(NO3)2 and characterized by H2-temperature-programmed reduction (TPR), NH3-temperature-programmed desorption (TPD), and diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS). Quadruple exchange of NH4-Beta at 70 °C resulted in 2.5 wt.% Ni loading corresponding to a Ni2+/framework aluminum (FAl) molar ratio of 0.52. [NiOH]+ and H+ are the primary charge-compensating cations in the uncalcined catalyst, as evidenced by TPR and DRIFTS. Subsequent calcination at 550 °C in air yielded a Ni-H-Beta catalyst containing primarily bare Ni2+ ions bonded to framework oxygens. Quadruple exchange of H-Beta at 70 °C gave 2.0 wt.% Ni loading (Ni2+/FAl = 0.41). After calcination at 550 °C, the resulting Ni-H-Beta catalyst comprises a mixture of bare Ni2+ ions: [NiOH]+ and NiO species. The relative abundance of [NiOH]+ increases with the number of exchanges. In situ pretreatment at 500 °C in flowing He converted the [NiOH]+ species to bare Ni2+ ions via dehydration. The bare Ni2+ ions interact strongly with the Beta framework as evidenced by a perturbed antisymmetric T-O-T vibration at 945 cm−1. DRIFT spectra of CO adsorbed at 20 °C indicate that the Ni2+ ions occupy two distinct exchange positions. The results of EO testing at 225 °C and 11 bar (ethylene) suggested that the specific Ni2+ species initially presented (e.g., bare Ni2+, [NiOH]+) did not significantly affect the catalytic performance.}, number={8}, journal={CATALYSTS}, author={McCaig, Joseph and Lamb, H. Henry}, year={2022}, month={Aug} }
 @article{novotny_lamb_2021, title={MoO3 films grown on stepped sapphire (0001) by molecular beam epitaxy}, volume={39}, ISSN={["1520-8559"]}, DOI={10.1116/6.0000962}, abstractNote={MoO3 films were grown on stepped c-plane sapphire substrates by molecular beam epitaxy using MoO3 vapor from a conventional Knudsen cell. Stepped sapphire (0001) substrates were prepared by ex situ annealing at 1100–1300 °C in dry air. Step bunching typically resulted in multistepped surfaces with wide atomically smooth terraces. Ex situ annealing at 1100 °C followed by in vacuo annealing at 700 °C provided clean substrates for growth. Ultrathin films were grown at 450 °C via a self-limiting process that represents a balance between the incident MoO3 flux and the desorption flux. Elongated bilayer islands (0.7-nm thick) were formed on sapphire (0001) terraces. Monocrystalline α-MoO3 (010) thin films [(010)α-MoO3∥(0001)sapphire] were grown at 450 °C using a higher incident MoO3 flux and characterized by atomic force microscopy, x-ray photoelectron spectroscopy, x-ray diffraction, and cross-sectional transmission electron microscopy. The step-terrace surface morphology of the monocrystalline films strongly suggests multilayer growth.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Novotny, Petr and Lamb, H. Henry}, year={2021}, month={Jul} }
 @article{cooper_dooley_fierro-gonzalez_guzman_jentoft_lamb_ogino_runnebaum_sapre_uzun_2020, title={Bruce Gates: A Career in Catalysis}, volume={10}, ISSN={["2155-5435"]}, DOI={10.1021/acscatal.0c03568}, abstractNote={On the occasion of his 80th birthday, we take stock of the remarkable and ongoing career of Professor Bruce C. Gates. This Account highlights his key scientific achievements in three areas of signi...}, number={20}, journal={ACS CATALYSIS}, author={Cooper, Cawas and Dooley, Kerry M. and Fierro-Gonzalez, Juan C. and Guzman, Javier and Jentoft, Rolf and Lamb, H. Henry and Ogino, Isao and Runnebaum, Ron C. and Sapre, Ajit and Uzun, Alper}, year={2020}, month={Oct}, pages={11912–11935} }
 @article{novotny_yusuf_li_lamb_2020, title={MoO3/Al2O3 catalysts for chemical-looping oxidative dehydrogenation of ethane}, volume={152}, ISSN={["1089-7690"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85078845301&partnerID=MN8TOARS}, DOI={10.1063/1.5135920}, abstractNote={MoO3/γ-Al2O3 catalysts containing 0.3–3 monolayer (ML) equivalents of MoO3 were prepared, characterized, and tested for ethane oxidative dehydrogenation (ODH) in cyclic redox and co-feed modes. Submonolayer catalysts contain highly dispersed (2D) polymolybdate structures; a complete monolayer and bulk Al2(MoO4)3 are present at >1ML loadings. High ethylene selectivity (>90%) in chemical looping (CL) ODH correlates with Mo+VI to Mo+V reduction; COx selectivity is <10% under these conditions. Mo+V and Mo+IV species trigger CH4 production resulting in much higher conversion albeit with <20% selectivity. In CL-ODH, submonolayer catalysts exhibit ethylene selectivities that decrease linearly from 96% at near-zero conversion to 70% at 45% conversion. >1ML catalysts provide higher conversions albeit with 10%–18% lower selectivity and greater selectivity loss with increasing conversion. In co-feed mode, ethylene selectivity drops to <50% at 46% conversion for a 0.6ML catalyst, but selectivity is virtually unaltered for a 3ML catalyst. We infer that at <1ML loadings, small domain size and strong Mo—O—Al bonds decrease 2D polymolybdate reducibility and enhance ethylene selectivity in CL-ODH.}, number={4}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Novotny, Petr and Yusuf, Seif and Li, Fanxing and Lamb, H. Henry}, year={2020}, month={Jan} }
 @article{neal_haribal_mccaig_lamb_li_2019, title={Modular‐scale ethane to liquids via chemical looping oxidative dehydrogenation: Redox catalyst performance and process analysis}, volume={1}, ISSN={2637-403X 2637-403X}, url={http://dx.doi.org/10.1002/AMP2.10015}, DOI={10.1002/AMP2.10015}, abstractNote={Abstract}, number={1-2}, journal={Journal of Advanced Manufacturing and Processing}, publisher={Wiley}, author={Neal, Luke and Haribal, Vasudev and McCaig, Joseph and Lamb, H. Henry and Li, Fanxing}, year={2019}, month={Apr}, pages={e10015} }
 @article{novotny_lamb_2019, title={Nanostructured MoOx films deposited on c-plane sapphire}, volume={37}, ISSN={["1520-8559"]}, DOI={10.1116/1.5100752}, abstractNote={Molybdenum oxide films were deposited on α-Al2O3 (0001) at 580 °C using MoO3 from a conventional molecular beam epitaxy Knudsen cell. A relatively smooth film (RMS roughness 1.1 nm) was deposited in 1 min at 580 °C using a Knudsen cell temperature of 620 °C; however, after 15 min deposition under these conditions, isolated islands (30–50 nm wide × 10–20 nm tall) develop that are stable to annealing at 600 °C for 60 min. XPS evidenced that the films are oxygen deficient with an average formula of MoO2.7. The authors infer that this oxygen deficiency is responsible for their thermal stability and may have significant effects on their catalytic and electronic properties. In contrast, stoichiometric MoO3 films deposited at 400 °C sublime completely during annealing at 600 °C.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Novotny, Petr and Lamb, H. Henry}, year={2019}, month={Sep} }
 @article{schulz_oelschlager_thompson_vermaas_nielsen_lamb_2018, title={Catalytic conversion of cyanobacteria-derived fatty acids to alkanes for biorenewable synthetic paraffinic kerosene}, volume={2}, ISSN={["2398-4902"]}, DOI={10.1039/c7se00558j}, abstractNote={A two-step catalytic process for converting cyanobacteria-derived fatty acids to linear and branched alkanes for synthetic paraffinic kerosene was demonstrated.}, number={4}, journal={SUSTAINABLE ENERGY & FUELS}, author={Schulz, Taylor C. and Oelschlager, Mason and Thompson, Simon T. and Vermaas, Wim F. J. and Nielsen, David R. and Lamb, H. Henry}, year={2018}, month={Apr}, pages={882–893} }
 @article{yusuf_neal_haribal_baldwin_lamb_li_2018, title={Manganese silicate based redox catalysts for greener ethylene production via chemical looping - oxidative dehydrogenation of ethane}, volume={232}, ISSN={["1873-3883"]}, url={http://dx.doi.org/10.1016/j.apcatb.2018.03.037}, DOI={10.1016/j.apcatb.2018.03.037}, abstractNote={The current study investigates manganese silicate based redox catalysts for ethane to ethylene conversion in a chemical looping oxidative dehydrogenation (CL-ODH) process. Facilitated by a two-step cyclic redox scheme, CL-ODH has the potential to overcome the drawbacks of traditional steam cracking including high energy consumption, coke formation, and significant CO2 and NOx emissions. In CL-ODH, lattice oxygen in manganese silicate based redox catalysts is used to combust the hydrogen formed from ethane dehydrogenation, enhancing ethylene formation and suppressing coke formation. The oxygen-deprived redox catalyst is subsequently regenerated with air, releasing heat to balance the overall heat requirement. The key to this process is an efficient redox catalyst with high selectivity and facile oxygen transport. In this study, redox catalysts with combined manganese and silica phases were tested. We report that redox catalysts with high manganese content are more effective for CL-ODH due to their higher oxygen capacity at reaction temperatures. Sodium tungstate was used as a promoter due to its effectiveness to suppress COx formation. Among the redox catalysts investigated, sodium tungstate promoted (1.7 wt.% Na) manganese silicate (Mn:Si molar ratio = 70:30) was the most effective, showing an ethylene selectivity of 82.6% and yield of 63.3%. Temperature programmed reaction (TPR) experiments indicate that the sodium tungstate promoter inhibits ethane activation on the surface of the redox catalyst and is selective towards hydrogen combustion. XPS analysis indicates that the manganese silicate redox catalysts have a smaller amount of near surface Mn4+ than previously studied manganese containing redox catalysts, leading to higher ethylene selectivity on the un-promoted redox catalysts. XPS also indicates that the reduction of the un-promoted redox catalysts leads to the consumption of silica and formation of inosilicate species. ASPEN Plus® simulations of the CL-ODH scheme using manganese silicate based redox catalysts indicate significant energy and emissions savings compared to traditional steam cracking: the overall energy consumption for ethylene production can potentially be reduced by 89% using the manganese silicate based redox catalyst in the CL-ODH process. Resulting from the significant energy savings, CO2/NOx emissions can be reduced by nearly one order of magnitude when compared to traditional steam cracking.}, journal={APPLIED CATALYSIS B-ENVIRONMENTAL}, author={Yusuf, Seif and Neal, Luke and Haribal, Vasudev and Baldwin, Madison and Lamb, H. Henry and Li, Fanxing}, year={2018}, month={Sep}, pages={77–85} }
 @article{barton_carrier_segura_fierro_park_lamb_escalona_peretti_2018, title={Ni/HZSM-5 catalyst preparation by deposition-precipitation. Part 2. Catalytic hydrodeoxygenation reactions of lignin model compounds in organic and aqueous systems}, volume={562}, ISSN={0926-860X}, url={http://dx.doi.org/10.1016/J.APCATA.2018.06.012}, DOI={10.1016/J.APCATA.2018.06.012}, abstractNote={Nickel metal supported on HZSM-5 (zeolite) is a promising catalyst for lignin depolymerization. In this work, the ability of catalysts prepared via deposition-precipitation (DP) to perform hydrodeoxygenation (HDO) on two lignin model compounds in organic and aqueous solvents was evaluated; guaiacol in dodecane and 2-phenoxy-1-phenylethanol (PPE) in aqueous solutions. All Ni/HZSM-5 catalysts were capable of guaiacol HDO into cyclohexane at 523 K. The role of the HZSM-5 acid sites was confirmed by comparison with Ni/SiO2 (inert support) which exhibited incomplete deoxygenation of guaiacol due to the inability to perform the cyclohexanol dehydration step. The catalyst prepared with 15 wt% Ni, a DP time of 16 h, and a calcination temperature of 673 K (Ni(15)/HZSM-5 DP16_Cal673), performed the guaiacol conversion with the greatest selectivity towards HDO products, with an intrinsic rate ratio (HDO rate to conversion rate) of 0.31, and 90% selectivity to cyclohexane. Catalytic activity and selectivity of Ni/HZSM-5 (15 wt%) in aqueous environments (water and 0.1 M NaOH solution) was confirmed using PPE reactions at 523 K. After 30 min reaction time in water, Ni/HZSM-5 exhibited ∼100% conversion of PPE, and good yield of the desired products; ethylbenzene and phenol (∼35% and 23% of initial carbon, respectively). Ni/HZSM-5 in NaOH solution resulted in significantly higher ring saturation compared to the Ni/HZSM-5 in water or the NaOH solution control.}, journal={Applied Catalysis A: General}, publisher={Elsevier BV}, author={Barton, R.R. and Carrier, M. and Segura, C. and Fierro, J.L.G. and Park, S. and Lamb, H.H. and Escalona, N. and Peretti, S.W.}, year={2018}, month={Jul}, pages={294–309} }
 @article{novotny_yusuf_li_lamb_2018, title={Oxidative dehydrogenation of ethane using MoO3/Fe2O3 catalysts in a cyclic redox mode}, volume={317}, ISSN={["1873-4308"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042634041&partnerID=MN8TOARS}, DOI={10.1016/j.cattod.2018.02.046}, abstractNote={Oxidative dehydrogenation (ODH) of ethane offers large reductions in energy consumption and associated greenhouse gas emissions when compared to conventional steam cracking for ethylene production; however, catalytic ODH of ethane using co-fed O2 requires expensive air separation. As an alternative, we are investigating novel core-shell catalysts that utilize lattice oxygen (O2−) as the sole oxidant and operate in a cyclic redox mode. In this work, redox catalysts having 1, 3 and 6 monolayer (ML) equivalents of MoO3 on α-Fe2O3 and a stoichiometric ferric molybdate, Fe2(MoO4)3, were prepared, characterized by powder x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS), and temperature-programmed reduction (TPR) and evaluated for ethane ODH in a cyclic redox mode at 600 °C. The characterization data are consistent with a core-shell structure for the calcined MoO3/Fe2O3 catalysts with a mixed Mo-Fe oxide surface layer. H2 and ethane TPR evidence that the shell inhibits Fe2O3 reduction and decreases the ethane combustion activity of the fully oxidized catalyst. Covering the Fe2O3 core with MoO3 also increases ODH activity and ethylene selectivity. In cyclic redox mode at 600 °C, ethylene selectivity was 57–62% for catalysts with 3 and 6 ML equivalents of MoO3.}, journal={CATALYSIS TODAY}, author={Novotny, Petr and Yusuf, Seif and Li, Fanxing and Lamb, H. Henry}, year={2018}, month={Nov}, pages={50–55} }
 @article{thompson_lamb_2018, title={Vapor-phase hydrodeoxygenation of guaiacol over carbon-supported Pd, Re and PdRe catalysts}, volume={563}, ISSN={0926-860X}, url={http://dx.doi.org/10.1016/J.APCATA.2018.06.031}, DOI={10.1016/J.APCATA.2018.06.031}, abstractNote={Vapor-phase hydrodeoxygenation (HDO) of guaiacol was investigated over a commercial Pd/C (A) catalyst (Evonik) and Pd/C (B), Re/C and PdRe/C catalysts prepared by incipient wetness impregnation of Norit SX-1 G activated carbon. The Pd/C catalysts had equivalent dispersions after reduction at 300 °C; however, Pd/C (B) had very low dispersion after reduction at 400 °C. CO chemisorption, Re LIII edge extended x-ray absorption fine structure (EXAFS) spectroscopy, and high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM) of the Re/C catalyst after reduction at 400 °C evidenced the formation of supported Re clusters. EXAFS spectroscopy of the PdRe/C catalyst after in situ reduction at 300 °C indicated the presence of Pd nanoparticles and Re clusters; a 2.70 Å Pd-Re contribution was required to adequately fit the Re LIII EXAFS spectrum. HAADF-STEM with energy-dispersive x-ray (EDX) analysis of the PdRe/C catalyst after reduction at 400 °C revealed Re clusters and Pd nanoparticles, some in intimate contact. In guaiacol HDO at 300 °C and 1 atm, Pd/C (A) was selective to phenol and cyclohexan-one/-ol and did not produce significant yields of benzene and cyclohexane, despite its high activity. Turnover frequencies for phenol (and cyclohexan-one/-ol) formation over the Pd/C catalysts were equivalent. Phenol, benzene and anisole were major products over Re/C after in situ reduction at 400 °C. The highest yield (52%) of fully deoxygenated products was obtained over PdRe/C after in situ reduction at 400 °C. We infer that the bimetallic catalyst combines synergistically the demethoxylation and hydrogenation functions of Pd/C with the capability of Re/C to deoxygenate phenol [Ghampson, et al., Catal. Sci. Technol. 2016].}, journal={Applied Catalysis A: General}, publisher={Elsevier BV}, author={Thompson, Simon T. and Lamb, H. Henry}, year={2018}, month={Aug}, pages={105–117} }
 @article{thompson_lamb_2017, title={Catalysts for selective hydrogenation of furfural derived from the double complex salt [Pd(NH3)(4)](ReO4)(2) on gamma-Al2O3}, volume={350}, ISSN={["1090-2694"]}, DOI={10.1016/j.jcat.2017.03.019}, abstractNote={The double complex salt [Pd(NH3)4](ReO4)2 was employed as precursor of supported bimetallic catalysts for selective hydrogenation of furfural. Direct reduction of [Pd(NH3)4](ReO4)2 on γ-Al2O3 in flowing H2 at 400 °C yields bimetallic nanoparticles 1–2 nm in size that exhibit significant interaction between the metals, as evidenced by temperature-programmed hydride decomposition (complete suppression of β-PdHx formation), extended X-ray absorption fine structure spectroscopy at the Pd K and Re LIII edges (PdRe distance = 2.72 Å), and scanning transmission electron microscopy with energy dispersive X-ray analysis. In contrast, calcination of [Pd(NH3)4](ReO4)2 on γ-Al2O3 at 350 °C in air and subsequent reduction in H2 at 400 °C results in metal segregation and formation of large (>50 nm) supported Pd particles; Re species cover the Pd particles and γ-Al2O3 support. A PdRe 1:2 catalyst prepared by sequential impregnation and calcination using HReO4 and [Pd(NH3)4](NO3)2 has a similar morphology. The catalyst derived by direct reduction of [Pd(NH3)4](ReO4)2 on γ-Al2O3 exhibits remarkably high activity for selective hydrogenation of furfural to furfuryl alcohol (FAL) at 150 °C and 1 atm. Suppression of H2 chemisorption via elimination of Pd threefold sites, as evidenced by CO diffuse-reflectance infrared Fourier transform spectroscopy, correlates with increased FAL selectivity.}, journal={JOURNAL OF CATALYSIS}, author={Thompson, Simon T. and Lamb, H. Henry}, year={2017}, month={Jun}, pages={111–121} }
 @article{thompson_lamb_delley_franzen_2017, title={Vibrational spectroscopy of the double complex salt Pd(NH3)4(ReO4)2, a bimetallic catalyst precursor}, volume={173}, ISSN={1386-1425}, url={http://dx.doi.org/10.1016/J.SAA.2016.10.011}, DOI={10.1016/j.saa.2016.10.011}, abstractNote={Tetraamminepalladium(II) perrhenate, a double complex salt, has significant utility in PdRe catalyst preparation; however, the vibrational spectra of this readily prepared compound have not been described in the literature. Herein, we present the infrared (IR) and Raman spectra of tetraamminepalladium(II) perrhenate and several related compounds. The experimental spectra are complemented by an analysis of normal vibrational modes that compares the experimentally obtained spectra with spectra calculated using DFT (DMol3). The spectra are dominated by features due to the ammine groups and the ReO stretch in Td ReO4-; lattice vibrations due to the D4h Pd(NH3)42+ are also observed in the Raman spectrum. Generally, we observe good agreement between ab initio calculations and experimental spectra. The calculated IR spectrum closely matches experimental results for peak positions and their relative intensities. The methods for calculating resonance Raman intensities are implemented using the time correlator formalism using two methods to obtain the excited state displacements and electron-vibration coupling constants, which are the needed inputs in addition to the normal mode wave numbers. Calculated excited state energy surfaces of Raman-active modes correctly predict relative intensities of the peaks and Franck-Condon activity; however, the position of Raman bands are predicted at lower frequencies than observed. Factor group splitting of Raman peaks observed in spectra of pure compounds is not predicted by DFT.}, journal={Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy}, publisher={Elsevier BV}, author={Thompson, Simon T. and Lamb, H. Henry and Delley, Bernard and Franzen, Stefan}, year={2017}, month={Feb}, pages={618–624} }
 @article{sun_schulz_thompson_lamb_2016, title={Catalytic deoxygenation of octanoic acid over silica- and carbon-supported palladium: Support effects and reaction pathways}, volume={269}, ISSN={["1873-4308"]}, DOI={10.1016/j.cattod.2015.12.021}, abstractNote={Octanoic acid (OA) deoxygenation was investigated over silica- and carbon-supported palladium catalysts (each containing 5 wt.% Pd) at 235–300 °C and 1 atm in a continuous flow reactor. A commercial Pd/SiO2 (A) catalyst was active for OA decarbonylation (DCN) and hydrodeoxygenation (HDO) at 260 °C under 10% H2; subsequent hydrogenation (HY) and DCN of the primary products, 1-heptene and octanal, respectively, produced n-heptane. Under equivalent conditions, a Pd/SiO2 (B) catalyst prepared using Pd(NO3)2 and Aerosil 300 produced n-heptane with very high selectivity (>99%) via DCN/HY. In contrast, a commercial Pd/C (A) catalyst was highly active and selective to n-heptane (>98%) and CO2 (65%) under these conditions. Moreover, CO2 selectivity and n-heptane yield increased with reaction temperature consistent with direct decarboxylation (DCX). Increasing H2 partial pressure resulted in markedly lower activity and CO2 selectivity; however, Pd/C (A) had negligible activity under He. Pd/C (A) exhibited greater water–gas shift (WGS) activity than Pd/SiO2 (A); however, differences in WGS activity alone cannot explain the observed support effect. A more highly dispersed Pd/C (B) catalyst was more active at 260 °C under H2 than Pd/C (A); however, under 10% H2, it had lower activity, CO2 selectivity (55%), and stability. Pd/C (A) and Pd/C (B) have very similar textural properties, but Pd/C (A) has a much higher Na content. By comparison, Pd supported on high-purity acetylene carbon black exhibited only DCN activity. These results indicate that carbon surface properties (e.g., polar functional groups, alkali metal content) influence the fatty acid deoxygenation performance of Pd/C catalysts.}, journal={CATALYSIS TODAY}, author={Sun, Keyi and Schulz, Taylor C. and Thompson, Simon T. and Lamb, H. Henry}, year={2016}, month={Jul}, pages={93–102} }
 @article{thompson_lamb_2016, title={Palladium-Rhenium Catalysts for Selective Hydrogenation of Furfural: Evidence for an Optimum Surface Composition}, volume={6}, ISSN={["2155-5435"]}, DOI={10.1021/acscatal.6b01398}, abstractNote={Bimetallic catalysts comprising a platinum-group metal (e.g., Pt, Pd, Ru) and rhenium (Re) have important applications in petroleum refining, industrial chemicals production, and biomass conversion. In this work, a series of PdRe/Al2O3 catalysts was investigated for selective hydrogenation of furfural to furfuryl alcohol (FAL) at 150 °C and 1 atm in a differential reactor. The results demonstrate that PdRe/Al2O3 catalysts have greater FAL selectivity and activity than Pd/Al2O3 catalysts. Over the bimetallic catalysts, decreased furan production is accompanied by a marked increase in hydrogenation activity. PdRe 1:1 catalysts prepared using [Pd(NH3)4](NO3)2 are significantly more active than catalysts prepared using Pd(NO3)2. PdRe 1:2 catalysts are more selective to FAL but less active than 1:1 catalysts prepared using the same precursors. The superior activity of PdRe/Al2O3 catalysts for selective hydrogenation of furfural is inferred to result from Re surface modification of Pd nanoparticles—disrupting P...}, number={11}, journal={ACS CATALYSIS}, author={Thompson, Simon T. and Lamb, H. Henry}, year={2016}, month={Nov}, pages={7438–7447} }
 @article{sun_wilson_thompson_lamb_2015, title={Catalytic Deoxygenation of Octanoic Acid over Supported Palladium: Effects of Particle Size and Alloying with Gold}, volume={5}, ISSN={["2155-5435"]}, DOI={10.1021/cs501865n}, abstractNote={Catalytic deoxygenation of octanoic acid (OA) to n-heptane was investigated over silica-supported Pd and PdAu catalysts at 260 °C and 1 atm in a fixed-bed microreactor. Pd/SiO2 catalysts were prepared by incipient wetness (IW) and ion exchange (IE). Bimetallic catalysts were prepared using an IE procedure that is known to produce supported PdAu nanoparticles. The Pd nanoparticles (7.5 nm average size) in the Pd/SiO2 (IW) catalyst exhibit well-defined (100) and (111) facets, as evidenced by high-resolution electron microscopy (HREM) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed CO. As expected, the smaller nanoparticles (1.5 nm average size) in the Pd/SiO2 (IE) catalyst display strong linear and bridging CO DRIFTS bands. The PdAu/SiO2 (1/1 atomic ratio) catalyst contains 5 nm alloy nanoparticles with Pd-rich surfaces, as evidenced by HREM with energy-dispersive X-ray (EDX) analysis and in situ EXAFS spectroscopy. DRIFTS thermal desorption experiments demonstrated that...}, number={3}, journal={ACS CATALYSIS}, author={Sun, Keyi and Wilson, Adria R. and Thompson, Simon T. and Lamb, H. Henry}, year={2015}, month={Mar}, pages={1939–1948} }
 @article{wang_allen_campos_cade_dean_dvora_immer_mixson_srirangan_sauer_et al._2013, title={ASI:Dunaliellamarine microalgae to drop-in replacement liquid transportation fuel}, volume={32}, ISSN={1944-7442}, url={http://dx.doi.org/10.1002/EP.11855}, DOI={10.1002/EP.11855}, abstractNote={Microalgae are a promising biofuels feedstock, theoretically yielding concentrations of triacylglycerides (TAGs) per unit area that are far higher than traditional feedstocks due to their rapid growth. Dunaliella is particularly advantageous as a feedstock because it is currently commercially mass cultured, thrives in salt water, and has no cell wall. Fourteen strains of Dunaliella have been investigated for growth rates and lipid production in mass culture and tested for enhanced lipid production under a range of environmental stressors including salinity, pH, nitrogen and phosphorus limitation, and light regime. The nuclear genome has been sequenced for four of these strains, with the objective of increasing carbon flux through genetic engineering. Electroflocculation followed by osmotic membrane rupturing may be a very energy and cost efficient means of harvesting the lipid bodies from Dunaliella. A technically feasible and scalable thermo‐catalytic process to convert the lipids into replacements for liquid transportation fuels has been developed. The lipids were converted into long‐chain alkanes through continuous thermal hydrolysis followed by fed‐batch thermo‐catalytic decarboxylation. These alkanes can be reformed into renewable diesel via conventional catalytic hydrocarbon isomerization reactions to improve cold flow properties, if desired. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 916–925, 2013}, number={4}, journal={Environmental Progress & Sustainable Energy}, publisher={Wiley}, author={Wang, Wei-Cheng and Allen, Elle and Campos, Andrew A. and Cade, Rushyannah Killens and Dean, Lisa and Dvora, Mia and Immer, Jeremy G. and Mixson, Stephanie and Srirangan, Soundarya and Sauer, Marie-Laure and et al.}, year={2013}, month={Sep}, pages={916–925} }
 @article{wilson_sun_chi_white_lebeau_lamb_wiley_2013, title={From Core-Shell to Alloys: The Preparation and Characterization of Solution-Synthesized AuPd Nanoparticle Catalysts}, volume={117}, ISSN={["1932-7447"]}, DOI={10.1021/jp404157m}, abstractNote={This article describes the solution-phase synthesis of 4 nm gold nanoparticles with 0.7 atom-thick, 1.9 atom-thick, and 3.8 atom-thick layers of Pd on their surfaces. These well-defined core–shell nanoparticles were deposited on a silica support, calcined, and reduced at 300 °C to create alloyed nanoparticles containing 10.9, 20.2, and 28.5% Pd (w/w). Monometallic Pd nanoparticles sintered during calcination at 300 °C, but no sintering was observed for AuPd nanoparticles. Diffuse reflectance infrared Fourier transform (DRIFT) spectra of adsorbed CO suggests that Au donates d electron density to Pd in the core–shell and alloy structures and confirms the presence of Au and Pd atoms on the surface of the nanoparticles after calcination and reduction. The properties of the AuPd alloy catalysts were tested in the vapor-phase conversion of α-limonene to p-cymene. AuPd nanoparticles containing 20% or more Pd per particle produced p-cymene yields greater than 80%, equivalent to conventional Pd catalysts prepared ...}, number={34}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Wilson, Adria R. and Sun, Keyi and Chi, Miaofang and White, Ryan M. and LeBeau, James M. and Lamb, H. Henry and Wiley, Benjamin J.}, year={2013}, month={Aug}, pages={17557–17566} }
 @article{lamb_sremaniak_whitten_2013, title={Reaction pathways for butanoic acid decarboxylation on the (111) surface of a Pd nanoparticle}, volume={607}, ISSN={0039-6028}, url={http://dx.doi.org/10.1016/j.susc.2012.08.023}, DOI={10.1016/j.susc.2012.08.023}, abstractNote={Many-electron theory is applied to investigate decarboxylation of butanoic acid on the (111) surface of a Pd42 nanoparticle. Butanoic acid adsorbs weakly as an intact molecule (ΔH = − 28 kJ/mol) with the COOH moiety nearly parallel to the surface. In comparison, dissociative adsorption of butanoic acid to form surface butanoate (PrCOO) species and adsorbed H is exothermic by only 5 kJ/mol. Pathways for propane and CO2 formation are presented starting from adsorbed butanoic acid, PrCOO (ads) and a RCHCOO (R = C2H5) surface intermediate. An intramolecular pathway involves rotating the H of COOH toward the target (alpha) carbon. Following a series of bond distortions, the H is close enough to the target C to form a stretched HC bond. After propane begins to form, CO2 linearizes and CC dissociation is energetically favorable and rapid. Reaction of PrCOO (ads) and H (ads) also results in direct formation of propane and CO2. The energy barriers for H insertion are ~ 100 kJ/mol for both pathways; however, the dissociative pathway involves a high-energy precursor state with H in a 3-fold site under the CC bond undergoing reaction. An alternative decarboxylation pathway starting from RCHCOO leads to gas-phase CO2 and propylidene (in the absence of adsorbed H) or propyl (via insertion of adsorbed H) with energy barriers of 75 and 32 kJ/mol, respectively. The energy of the RCHCOO intermediate relative to gas-phase butanoic acid increases from 43 to 109 kJ/mol in the presence of adsorbed H, compensating for the lower decomposition barrier.}, journal={Surface Science}, publisher={Elsevier BV}, author={Lamb, H. Henry and Sremaniak, Laura and Whitten, Jerry L.}, year={2013}, month={Jan}, pages={130–137} }
 @article{gray_peretti_lamb_2013, title={Real-time monitoring of high-gravity corn mash fermentation using in situ raman spectroscopy}, volume={110}, ISSN={["1097-0290"]}, DOI={10.1002/bit.24849}, abstractNote={Abstract}, number={6}, journal={BIOTECHNOLOGY AND BIOENGINEERING}, author={Gray, Steven R. and Peretti, Steven W. and Lamb, H. Henry}, year={2013}, month={Jun}, pages={1654–1662} }
 @article{ford_thapaliya_kelly_roberts_lamb_2013, title={Semi-Batch Deoxygenation of Canola- and Lard-Derived Fatty Acids to Diesel-Range Hydrocarbons}, volume={27}, ISSN={["1520-5029"]}, DOI={10.1021/ef4016763}, abstractNote={Fatty acids (FAs) derived via thermal hydrolysis of food-grade lard and canola oil were deoxygenated in the liquid phase using a commercially available 5 wt % Pd/C catalyst. Online quadrupole mass spectrometry and gas chromatography were used to monitor the effluent gases from the semi-batch stirred autoclave reactors. Stearic, oleic, and palmitic acids were employed as model compounds. A catalyst lifetime exceeding 2200 turnovers for oleic acid deoxygenation was demonstrated at 300 °C and 15 atm under 10% H2. The initial decarboxylation rate of palmitic acid under 5% H2 decreases sharply with increasing initial concentration; in contrast, the initial decarbonylation rate increases linearly, indicative of first-order kinetics. Scale-up of diesel-range hydrocarbon production was investigated by increasing the reactor vessel size, initial FA concentration, and FA/catalyst mass ratio. Lower CO2 selectivity and batch productivity were observed at the larger scales (600 and 5000 mL), primarily because of the h...}, number={12}, journal={ENERGY & FUELS}, author={Ford, Jeffrey P. and Thapaliya, Nirajan and Kelly, M. Jason and Roberts, William L. and Lamb, H. Henry}, year={2013}, month={Dec}, pages={7489–7496} }
 @article{ford_immer_lamb_2012, title={Palladium Catalysts for Fatty Acid Deoxygenation: Influence of the Support and Fatty Acid Chain Length on Decarboxylation Kinetics}, volume={55}, ISSN={["1572-9028"]}, DOI={10.1007/s11244-012-9786-2}, number={3-4}, journal={TOPICS IN CATALYSIS}, author={Ford, Jeffrey P. and Immer, Jeremy G. and Lamb, H. Henry}, year={2012}, month={May}, pages={175–184} }
 @article{immer_kelly_lamb_2010, title={Catalytic reaction pathways in liquid-phase deoxygenation of C18 free fatty acids}, volume={375}, ISSN={["1873-3875"]}, DOI={10.1016/j.apcata.2009.12.028}, abstractNote={The liquid-phase deoxygenation of stearic, oleic, and linoleic acids employing a 5 wt% Pd/C catalyst was investigated using on-line quadrupole mass spectrometry (QMS). Catalytic deoxygenation of stearic acid (SA) under He occurs primarily via decarboxylation; the liquid products are n-heptadecane and heptadecenes. On-line QMS revealed concomitant CO2 and H2 evolution which can explain the greater than expected heptadecene yields at low to intermediate conversions. After essentially complete SA conversion, hydrogenation of heptadecenes via hydrogen transfer from the dodecane solvent results in 98% n-heptadecane yield. The initial rate of SA decarboxylation under 10% H2 is lower than under He; however, by avoiding the formation of unsaturated products the reaction requires much less time to reach completion. The SA decarboxylation rate under 10% H2 is 6-fold slower in heptadecane than in dodecane. This apparent solvent effect is explained by the lower vapor pressure of heptadecane resulting in greater H2 inhibition of the decarboxylation reaction. Our results demonstrate that the unsaturated C18 free fatty acids, oleic and linoleic, must be hydrogenated to SA before decarboxylation can proceed at a significant rate. Oleic acid (OA) deoxygenation under He occurs very slowly and primarily via decarbonylation. In contrast, OA deoxygenation under 10% H2 occurs facilely via hydrogenation to SA followed by decarboxylation. Since hydrogenation is complete during heating to reaction temperature, the decarboxylation kinetics and product yields are not affected by the initial unsaturation of the reactant.}, number={1}, journal={APPLIED CATALYSIS A-GENERAL}, author={Immer, Jeremy G. and Kelly, M. Jason and Lamb, H. Henry}, year={2010}, month={Feb}, pages={134–139} }
 @article{immer_lamb_2010, title={Fed-Batch Catalytic Deoxygenation of Free Fatty Acids}, volume={24}, ISSN={["1520-5029"]}, DOI={10.1021/ef100576z}, abstractNote={Fed-batch catalytic deoxygenation of C18 free fatty acids (FFAs) to n-heptadecane was demonstrated in a 50 mL stirred autoclave reactor with continuous FFA injection via a high-pressure syringe pump. High selectivity to the hydrogen-neutral decarboxylation pathway was achieved using a 5 wt % Pd/C catalyst at 300 °C under 5% H2 (15 atm total pressure); the maximum quasi-steady-state deoxygenation rate under these conditions was 0.46 mmol gcat−1 min−1 [0.083 s−1 turnover frequency (TOF)] with 95% CO2 selectivity. In a separate experiment, quasi-steady-state SA deoxygenation activity was maintained for >24 h at 0.29 mmol gcat−1 min−1 (0.053 s−1 TOF) with 92% CO2 selectivity. When higher H2 partial pressures were employed, an abrupt switchover in reaction pathway and product selectivity from decarboxylation (CO2) to decarbonylation (CO) was observed. Higher CO selectivity leads to increased H2 consumption because of hydrogenation of heptadecenes, the primary products of the decarbonylation pathway. We infer t...}, number={10}, journal={ENERGY & FUELS}, author={Immer, Jeremy G. and Lamb, H. Henry}, year={2010}, month={Oct}, pages={5291–5299} }
 @article{kelly_kim_roberts_lamb_2008, title={Characterization of Pd/gamma-Al2O3 Catalysts Prepared Using [Pd(hfac)(2)] in Liquid CO2}, volume={49}, ISSN={["1572-9028"]}, DOI={10.1007/s11244-008-9075-2}, number={3-4}, journal={TOPICS IN CATALYSIS}, author={Kelly, M. Jason and Kim, Jaehoon and Roberts, George W. and Lamb, H. Henry}, year={2008}, month={Aug}, pages={178–186} }
 @article{kim_kelly_lamb_roberts_kiserow_2008, title={Characterization of palladium (Pd) on alumina catalysts prepared using liquid carbon dioxide}, volume={112}, ISSN={["1932-7447"]}, DOI={10.1021/jp711495n}, abstractNote={Palladium (II) hexafluoroacetylacetonate (Pd(hfac)2) dissolved in liquid carbon dioxide (L-CO2) was used to deposit Pd nanoparticles onto low-surface-area α-alumina (13 m2/g) and high-surface-area γ-alumina (207 m2/g). These nanoparticles were prepared by contacting Pd(hfac)2 dissolved in L-CO2 with the alumina at 6.9 MPa and 28.5 °C and then slowly venting gaseous CO2 until L-CO2 was completely evaporated. After depressurization to remove the CO2 and unabsorbed Pd(hfac)2, the impregnated Pd(hfac)2 was reduced in hydrogen at a relatively low temperature of 75 °C. The adsorption isotherm of Pd(hfac)2 on γ-alumina suggests a weak interaction between the organometallic compound and the support. The average Pd particle size on the low-surface-area α-alumina, measured by scanning electron microscopy, increased from 13.1 ± 3.5 to 59.9 ± 11.3 nm, and the metal dispersion, measured by pulsed CO chemisorption, decreased from 11 to 3%, as the Pd loading on the alumina was increased from 0.15 to 1.54 wt %. With the ...}, number={28}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Kim, Jaehoon and Kelly, M. Jason and Lamb, H. Henry and Roberts, George W. and Kiserow, Douglas J.}, year={2008}, month={Jul}, pages={10446–10452} }
 @article{campos_spivey_roy_lohitharn_goodwin_lotero_lamb_2007, title={Characterization of Mo additions in iron-based Fischer–Tropsch catalysts using X-ray absorption spectroscopy and X-ray diffraction}, volume={582}, ISSN={0168-9002}, url={http://dx.doi.org/10.1016/j.nima.2007.08.135}, DOI={10.1016/j.nima.2007.08.135}, abstractNote={An iron-based Fischer–Tropsch catalyst with a low concentration of molybdenum (90Fe/10Mo/5Cu/17Si) used as a promoter was characterized by X-ray absorption spectroscopy (XAS) and X-ray diffractometry (XRD). The catalyst was prepared using coprecipitation, pretreated in CO, then one sample passivated and one calcined. The XRD data show that after CO pretreatment the calcined and passivated catalysts are almost amorphous with respect to Fe2O3 with nanoparticle size of 10 and 100 Å for Fe3C (only present in the passivated sample). Least squares fitting of the XANES region show that the calcined and passivated samples were similar in the bulk and surface structures, with the calcined samples completely oxidized. As expected, K and LIII edges Mo-XANES shows only small molybdenum carbide formation compared to iron carbide.}, number={1}, journal={Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, publisher={Elsevier BV}, author={Campos, A. and Spivey, J.J. and Roy, A. and Lohitharn, N. and Goodwin, J. and Lotero, E. and Lamb, H.}, year={2007}, month={Nov}, pages={236–238} }
 @article{silletti_adams_sigmon_nikolopoulos_spivey_lamb_2006, title={A novel Pd/MgAlOx catalyst for NOx storage-reduction}, volume={114}, ISSN={["1873-4308"]}, DOI={10.1016/j.cattod.2006.02.003}, abstractNote={A novel NOx storage-reduction catalyst consisting of Pd dispersed on a magnesium–aluminum oxide (MgAlOx) support is described. The MgAlOx support was prepared from a synthetic Mg/Al layered double hydroxide, and Pd bis-acetylacetonate (acac) was adsorbed onto the freshly calcined support from toluene. The Pd/MgAlOx catalyst was pretreated in either O2 or H2 at 500 °C to decompose the adsorbed [Pd(acac)2] and remove organic residues. NOx adsorption experiments were conducted at 300 °C using two gas mixtures: 500 ppm NO2, 6% O2 and 10% CO2 (bal. He) and 500 ppm NO, 500 ppm N2 and 5% O2 (bal. He). Temperature-programmed desorption (TPD) and diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS) evidence that NO2 adsorption on MgAlOx produces primarily surface nitrate species. The adsorption capacity of the support for NO + O2 is four-fold lower than for NO2. Temperature-programmed reduction (TPR) in flowing H2 demonstrates that surface nitrate and nitrite species on MgAlOx are reduced to N2 at 300–400 °C. The adsorption capacity of Pd/MgAlOx for NO + O2 is almost four-fold greater than MgAlOx evidencing a catalytic role of Pd in the NOx storage mechanism. TPR in flowing H2 indicates that the adsorbed NOx species are removed at very low temperatures (∼50 °C) suggesting that they are located near the catalytically active Pd sites.}, number={1}, journal={CATALYSIS TODAY}, author={Silletti, BA and Adams, RT and Sigmon, SM and Nikolopoulos, A and Spivey, JJ and Lamb, HH}, year={2006}, month={Apr}, pages={64–71} }
 @article{bayat_walter_lamb_marino_ferguson_ollier_2005, title={Mitochondrial mutation detection using enhanced multiplex denaturing high-performance liquid chromatography}, volume={32}, ISSN={["1744-313X"]}, DOI={10.1111/j.1744-313x.2005.00508.x}, abstractNote={Summary}, number={3}, journal={INTERNATIONAL JOURNAL OF IMMUNOGENETICS}, author={Bayat, A and Walter, J and Lamb, H and Marino, M and Ferguson, MWJ and Ollier, WER}, year={2005}, month={Jun}, pages={199–205} }
 @article{wang_spivey_lamb_2005, title={NO decomposition over a Pd/MgO catalyst prepared from [Pd(acac)(2)]}, volume={56}, ISSN={["1873-3883"]}, DOI={10.1016/j.apcatb.2004.09.014}, abstractNote={A Pd/MgO catalyst was prepared by adsorption of palladium bis-acetylacetonate [Pd(acac)2] onto highly dehydroxylated MgO from toluene solution and subsequent reduction in flowing H2 at 300 °C. The resultant catalyst was characterized by Pd K-edge X-ray absorption fine structure (XAFS) spectroscopy, temperature-programmed desorption (TPD), and Fourier transform infrared (FTIR) spectroscopy of adsorbed NO. The adsorbed [Pd(acac)2] species decomposes on heating in H2 to form 20–25 Å supported Pd particles; however, organic residues from the acetylacetonate ligands remain on the catalyst surface. The FTIR spectrum of NO adsorbed on the reduced Pd/MgO catalyst at 25 °C contains one principal band at 1722 cm−1 due to atop Pd nitrosyl species. In situ XAFS of the Pd/MgO catalyst indicates that neither Pd oxidation nor particle sintering occurs during heating in flowing 1% NO/He to 300 °C. NO decomposition over the Pd/MgO catalyst was investigated using temperature-programmed reaction spectroscopy (TPRS) and steady-state activity measurements. During the initial TPRS cycle in flowing 1% NO/He, nearly complete NO consumption occurs at ∼270 °C due to oxidation of organic residues. O2 evolution commences at approximately 350 °C, and steady-state catalytic decomposition of NO to N2 and O2 occurs at 600 °C. Transient NO consumption during rapid cooling in 1% NO/He (after steady-state catalysis) is attributed to NOx adsorption on the Pd/MgO catalyst.}, number={4}, journal={APPLIED CATALYSIS B-ENVIRONMENTAL}, author={Wang, XQ and Spivey, JJ and Lamb, HH}, year={2005}, month={Apr}, pages={261–268} }
 @article{wang_sigmon_spivey_lamb_2004, title={Support and particle size effects on direct NO decomposition over platinum}, volume={96}, ISSN={["1873-4308"]}, DOI={10.1016/j.cattod.2004.05.003}, abstractNote={Supported Pt catalysts were prepared by ion exchange of Pt(II) tetraamine hydroxide [Pt(NH3)4(OH)2] onto SiO2, Al2O3, and TiO2 and by adsorption of Pt bis-acetylacetonate [Pt(acac)2] onto MgO. All the catalysts except Pt/TiO2 were characterized by in situ X-ray absorption fine structure (XAFS) spectroscopy after reduction at 300 °C in flowing H2, and the Pt/SiO2 and Pt/MgO catalysts were examined after subsequent exposure to 1% NO/He at 25–300 °C. NO decomposition pathways were investigated by temperature-programmed reaction spectroscopy (TPRS) using a 1% NO/He feed, and steady-state conversions for direct NO decomposition were measured at 600 °C. NO decomposition at low temperatures (200–400 °C) produces N2O and N2, and in situ XAFS spectroscopy indicates that the supported Pt particles are partially oxidized under these conditions. Over each catalyst, O2 production begins at ∼350 °C; N2O production declines above 400 °C; and N2 and O2 are the only detectable NO decomposition products at 600 °C. Nanometer-sized Pt clusters on SiO2 sinter during heating in 1% NO/He at 300 °C, whereas larger Pt particles supported on SiO2 and MgO are resistant to sintering under these conditions. The turnover frequency for direct NO decomposition over Pt/SiO2 catalysts is insensitive to Pt particle size. Pt/SiO2, Pt/Al2O3, and Pt/TiO2 catalysts have equivalent NO decomposition activities suggesting the absence of support effects for these metal oxides. In contrast, the NO decomposition activity of Pt supported on strongly basic MgO is significantly lower.}, number={1-2}, journal={CATALYSIS TODAY}, author={Wang, XQ and Sigmon, SA and Spivey, JJ and Lamb, HH}, year={2004}, month={Oct}, pages={11–20} }
 @article{smith_lamb_mcginnis_davis_2004, title={Surface-roughness correlations in homoepitaxial growth of GaN(0001) films by NH3 supersonic jet epitaxy}, volume={96}, ISSN={["1089-7550"]}, DOI={10.1063/1.1785869}, abstractNote={Homoepitaxial GaN films were grown on GaN(0001)∕6H-SiC substrates by NH3 supersonic jet epitaxy at 750°C using a constant Ga flux of 2.9×1014cm−2s−1 and varying the NH3 flux and average kinetic energy. Atomic force microscopy (AFM), scanning electron microscopy, and in situ reflection high-energy electron diffraction evidence an abrupt transition from quasi-two-dimensional basal-plane growth to three-dimensional faceted growth at approximately 1∕2 of the maximum Ga-limited growth rate, irrespective of NH3 kinetic energy. Topographical scaling analysis of the AFM images reveals that the smooth and rough GaN(0001) films have static scaling exponents (α) of 0.88±0.05 and 1.10±0.06, respectively. The dynamic scaling exponent (β) for rough films is approximately 0.25. A comparison of these scaling exponents with predictions based on continuum growth models indicates that competition between surface diffusion and stochastic roughening governs the evolution of surface morphology during GaN growth.}, number={8}, journal={JOURNAL OF APPLIED PHYSICS}, author={Smith, NA and Lamb, HH and McGinnis, AJ and Davis, RF}, year={2004}, month={Oct}, pages={4556–4562} }
 @article{mcginnis_thomson_banks_preble_davis_lamb_2003, title={Supersonic jet epitaxy of gallium nitride using triethylgallium and ammonia}, volume={21}, ISSN={["0734-2101"]}, DOI={10.1116/1.1532736}, abstractNote={Gallium nitride (GaN) films were grown on GaN(0001)/AlN/6H–SiC composite substrates at 700–780 °C by supersonic jet epitaxy using triethylgallium (TEG) and NH3. TEG was seeded in He and N2 supersonic free jets to obtain kinetic energies of ∼2.1 and ∼0.5 eV, respectively, and NH3 was supplied from a variable leak valve. Higher TEG beam intensities (by about a factor of 5) were obtained by seeding in He. In situ reflection high-energy electron diffraction indicated a transition from three-dimensional to two-dimensional (2D) growth between 730 and 750 °C for films grown using TEG seeded in He and a constant NH3/TEG flux ratio. Ex situ atomic force microscopy of films grown at 730 and 750 °C revealed smooth surfaces comprised of quasi-2D islands with irregular perimeters. Cross-sectional transmission electron microscopy evidenced that the film grown at 750 °C was homoepitaxial α-GaN with a high density of planar lattice defects. Secondary ion mass spectrometry detected high residual carbon concentrations in the films. The GaN growth rate at 750 °C was found to depend on TEG flux and NH3 pressure in a manner consistent with Langmuir–Hinshelwood kinetics. Films grown under NH3-rich conditions were faceted and microscopically rough, whereas nonfaceted, basal-plane growth was observed under Ga-rich conditions. The first-order dependence of growth rate on TEG flux under NH3-rich conditions was used to estimate Ga incorporation efficiencies for high- and low-energy TEG beams. The Ga incorporation efficiency is lower for high-energy TEG beams, consistent with a decrease in the sticking coefficient for dissociative chemisorption.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={McGinnis, AJ and Thomson, D and Banks, A and Preble, E and Davis, RF and Lamb, HH}, year={2003}, pages={294–301} }
 @article{stallings_lamb_2003, title={Synthesis of nanostructured titania powders via hydrolysis of titanium isopropoxide in supercritical carbon dioxide}, volume={19}, ISSN={["0743-7463"]}, DOI={10.1021/la020760i}, abstractNote={Titania powders were synthesized via hydrolysis of titanium(IV) isopropoxide (TIP) in supercritical carbon dioxide (SCCD). Injection of TIP into water-in-CO2 (w/c) dispersions resulted in precipitation of spherical titania particles, and free-flowing white titania powders were isolated in 65−70% yield by slow isothermal depressurization. Qualitatively similar results were obtained with and without the addition of an anionic phosphate fluorosurfactant (DuPont Zonyl FSP) to stabilize the w/c dispersions. The titania powders had broad particle size distributions (20−800 nm) and specific surface areas in the 100−500 m2/g range. Addition of Zonyl FSP resulted in a decrease in specific surface area at a given water-to-alkoxide molar ratio (hydrolysis level). The specific surface area increased as the hydrolysis level was increased, irrespective of the presence of surfactant. The surface area is associated primarily with internal porosity of the spherical titania particles, as evidenced by scanning transmission ...}, number={7}, journal={LANGMUIR}, author={Stallings, WE and Lamb, HH}, year={2003}, month={Apr}, pages={2989–2994} }
 @article{khandelwal_niimi_lucovsky_lamb_2002, title={Low-temperature Ar/N-2 remote plasma nitridation of SiO2 thin films}, volume={20}, ISSN={["0734-2101"]}, DOI={10.1116/1.1513635}, abstractNote={Low-temperature nitridation of SiO2 thin films by Ar/N2 remote plasma processing was investigated using on-line Auger electron spectroscopy, angle-resolved x-ray photoelectron spectroscopy (ARXPS), and optical emission spectroscopy (OES). Nitridation experiments were performed at 300 °C using 30 W Ar/N2 remote plasmas at 0.1 and 0.3 Torr. Ar/N2 remote plasma exposure of 5 nm SiO2 films for 30 min results in nitrogen incorporation throughout the films, independent of process pressure and plasma reactor configuration (i.e., upstream versus downstream N2 injection). ARXPS indicates a N–Si3 local bonding configuration with second nearest neighbor oxygen atoms. Ar/N2 remote plasma exposure at 0.1 Torr results in higher nitrogen concentrations (8–10 at. %). Reactor configuration has a negligible effect at 0.1 Torr; conversely, downstream N2 injection results in higher nitrogen concentrations (5–6 at. %) than upstream injection (3–4 at. %) at 0.3 Torr. OES indicates that the Ar/N2 remote plasmas contain N2 triplet excited states and ground-state N atoms. The Ar emission intensities and the saturation N concentrations in the resultant films follow similar trends with processing pressure and reactor configuration; the N2 first positive emission intensities run counter to these trends. We infer that low-temperature SiO2 nitridation by Ar/N2 remote plasmas is a two-step process: O removal by Ar+ ion bombardment and N insertion by plasma-generated active N species. Moreover, the first step appears to be rate limiting under the conditions employed in this study. Annealing the oxynitride films in N2 at 900 °C decreases the N concentration and results in a more uniform nitrogen distribution.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Khandelwal, A and Niimi, H and Lucovsky, G and Lamb, HH}, year={2002}, pages={1989–1996} }
 @article{niimi_khandelwal_lamb_lucovsky_2002, title={Reaction pathways in remote plasma nitridation of ultrathin SiO2 films}, volume={91}, ISSN={["1089-7550"]}, DOI={10.1063/1.1419208}, abstractNote={Low-temperature nitridation of 3 nm SiO2 films using He/N2 and N2 remote radio frequency (rf) plasmas was investigated. On-line Auger electron spectroscopy and angle-resolved x-ray photoelectron spectroscopy (ARXPS) were employed to determine the concentration, spatial distribution, and local chemical bonding of nitrogen in the resultant films. Experiments were performed using a substrate temperature of 300 °C and 30 W rf power. Nitridation using an upstream He/N2 remote plasma at 0.1 Torr incorporates nitrogen at the top surface of the SiO2 film. In contrast, a lower concentration of nitrogen distributed throughout the film is obtained when the process pressure is increased to 0.3 Torr. ARXPS indicates a N–Si3 local bonding configuration, irrespective of the spatial distribution of N atoms. Slightly more nitrogen is incorporated using a downstream He/N2 plasma at each process pressure. By comparison, nitridation of SiO2 films using a N2 remote plasma at 0.1 Torr is very slow. Optical emission spectroscopy indicates that He dilution enhances the generation of N2+(B 2Σu+) species by altering the plasma electron energy distribution and by providing an additional kinetic pathway (Penning ionization). Changing the He/N2 remote plasma configuration from upstream to downstream (at 0.1 and 0.3 Torr) also enhances N2+(B 2Σu+) generation. For upstream He/N2 remote plasmas, the intensity of N2 first positive emission from N2(B 3Πg) states increases with pressure, whereas the N2+ first negative emission from N2+(B 2Σu+) states decreases. We infer from these observations that N2+ species are primarily responsible for top surface nitridation at 0.1 Torr, and that neutral species [N2(A 3Σu+) metastables and N atoms] are associated with sub-surface nitrogen incorporation.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Niimi, H and Khandelwal, A and Lamb, HH and Lucovsky, G}, year={2002}, month={Jan}, pages={48–55} }
 @article{mcginnis_thomson_davis_chen_michel_lamb_2001, title={In situ cleaning of GaN/6H-SiC substrates in NH3}, volume={222}, ISSN={["0022-0248"]}, DOI={10.1016/s0022-0248(00)00947-7}, abstractNote={Metalorganic chemical vapor deposition-grown GaN on 6H-SiC substrates were cleaned by annealing in an NH3 flux. Oxygen contamination was removed by thermal desorption, and carbon removal was facilitated by reaction with NH3. The GaN(0 0 0 1) surface after NH3 beam cleaning at 730°C was smooth with distinct atomic steps. The roughness (0.20 nm RMS) was only slightly greater than that of the untreated substrate (0.17 nm RMS). Carbon and oxygen concentrations were reduced to background levels (∼1 at%) by annealing in an NH3 flux at 800°C. The surface step structure was destroyed by annealing in an NH3 flux of 4×1015 cm−2 s−1 from a seeded supersonic beam; however, annealing in an NH3 flux of 7×1015 cm−2 s−1 from a leak valve inhibited surface roughening and produced a relatively smooth surface (0.28 nm RMS) with a 3×3 R30° reconstruction. We infer from the effects of annealing temperature and NH3 flux that the observed surface roughening is due to GaN decomposition.}, number={3}, journal={JOURNAL OF CRYSTAL GROWTH}, author={McGinnis, AJ and Thomson, D and Davis, RF and Chen, E and Michel, A and Lamb, HH}, year={2001}, month={Jan}, pages={452–458} }
 @article{mcginnis_thomson_davis_chen_michel_lamb_2001, title={Kinetics and gas-surface dynamics of GaN homoepitaxial growth using NH3-seeded supersonic molecular beams}, volume={494}, ISSN={["1879-2758"]}, DOI={10.1016/S0039-6028(01)01466-2}, abstractNote={The kinetics of homoepitaxial growth of GaN thin films on metal-organic chemical vapor deposition (MOCVD)-grown GaN(0 0 0 1)/AlN/6H-SiC substrates was probed using NH3-seeded supersonic molecular beams. NH3 was seeded in H2 and He and antiseeded in N2 and Ar in order to obtain incident kinetic energies of 0.08–1.8 eV. Nozzle temperatures of 35–600 °C were used to adjust the NH3 internal energy. Intense NH3 beams (fluxes >2×1015cm−2s−1 at the substrate) are produced for low seeding percentages (<5%) in the lighter carrier gases, because the heavier species (NH3) is focused along the centerline of the beam. The NH3 flux is proportional to the ratio of its molecular weight to the average molecular weight of the binary gas mixture. A steady-state Langmuir–Hinshelwood kinetics model was used to extract zero-coverage NH3 sticking coefficient (αNH30) values from GaN growth kinetics data. An αNH30 value of 0.14 at 750 °C was determined using seeded supersonic beams of NH3 in He with incident kinetic energies of 0.4–0.5 eV. In comparison, GaN growth rates using low-energy NH3 molecules (0.03 eV) from a leak valve indicate an αNH30 of 0.29. Growth rate measurements using NH3 beams with kinetic energies of 0.08–1.8 eV confirmed that αNH30 generally decreases with increasing incident kinetic energy, leading us to conclude that NH3 chemisorption on GaN(0 0 0 1) is unactivated and occurs via a precursor-mediated mechanism. Internal energy enhancement of NH3 chemisorption via a precursor-mediated channel is proposed to explain the effects of nozzle temperature on GaN growth kinetics. The effects of NH3 incident kinetic energy on film morphology are indirect. Rough, highly faceted films are observed under Ga-limited growth conditions. The surface morphology of films grown under NH3-limited conditions changes from rough to smooth as the effective V/III ratio is decreased.}, number={1}, journal={SURFACE SCIENCE}, author={McGinnis, AJ and Thomson, D and Davis, RF and Chen, E and Michel, A and Lamb, HH}, year={2001}, month={Nov}, pages={28–42} }
 @article{khandelwal_smith_lamb_2001, title={Nitrogen incorporation in ultrathin gate dielectrics: A comparison of He/N2O and He/N-2 remote plasma processes}, volume={90}, ISSN={["0021-8979"]}, DOI={10.1063/1.1397286}, abstractNote={Ultrathin Si oxynitride films grown by low-temperature remote plasma processing were examined by on-line Auger electron spectroscopy and angle-resolved x-ray photoelectron spectroscopy to determine the concentration, spatial distribution, and chemical bonding of nitrogen. The films were grown at 300 °C on Si(100) substrates using two radio-frequency remote plasma processes: (i) He/N2O remote plasma-assisted oxidation (RPAO) and (ii) two-step remote plasma oxidation/nitridation. A 5 min He/N2O RPAO process produces a 2.5 nm oxynitride film incorporating approximately 1 monolayer of nitrogen at the Si–SiO2 interface. The interfacial nitrogen is bonded in a N–Si3 configuration, as in silicon nitride (Si3N4). By comparison, a 90 s He/N2 remote plasma exposure of a 1 nm oxide (grown by 10 s He/O2 RPAO) consumes substrate Si atoms creating a 1 nm subcutaneous Si3N4 layer. The nitrogen areal density obtained via the two-step process depends on the initial oxide thickness and the He/N2 remote plasma exposure time. Moreover, as the oxide thickness is increased (by increasing the He/O2 remote plasma exposure), the nitrogen distribution shifts away from the Si–SiO2 interface and into the oxide. More nitrogen with a tighter distribution is incorporated using He versus Ar dilution. Insight into the remote plasma chemistry was provided by optical emission spectroscopy. Strong N2 first positive and second positive emission bands were observed for He/N2O and He/N2 remote plasmas indicating the presence of N2 metastables and ground-state N atoms.}, number={6}, journal={JOURNAL OF APPLIED PHYSICS}, author={Khandelwal, A and Smith, BC and Lamb, HH}, year={2001}, month={Sep}, pages={3100–3108} }
 @article{min_lamb_hauser_2001, title={Time-dependent Si etch behavior and its effect on oxide/Si selectivity in CF4+D-2 electron cyclotron resonance plasma etching}, volume={19}, ISSN={["1071-1023"]}, DOI={10.1116/1.1371318}, abstractNote={Transient poly-Si etching behavior in CF4+D2 electron cyclotron resonance plasmas containing different D2 proportions was investigated. Higher D2 proportions resulted in lower atomic F and higher CF2 concentration in the plasma, as evidenced by optical emission spectroscopy (OES), and in greater oxide-to-Si etch selectivity. A high initial poly-Si etch rate that declined very rapidly to a finite-steady-state value was observed for plasma etching under conditions giving low (3:1) oxide-to-Si etch selectivity. In contrast, a lower initial etch rate that declined to approximately zero over a longer (∼45 s) period was observed for poly-Si etching under plasma conditions giving (∼15:1) selectivity. In the latter case, Si consumption during overetching would be significantly underestimated if calculated on the basis of the conventional 60 s selectivity ration. X-ray photoelectron spectroscopy analysis indicated that a thick, more F-deficient fluorocarbon film was deposited on Si under the high-selectivity etching conditions. Real-time SiF4 and atomic F signals, which were measured during SiO2 etching using OES and mass spectroscopy, respectively, evidenced significantly different end-point trends for the high- and low-selectivity etching conditions. These trends are interpreted in light of the transient etching behavior observed for poly-Si under equivalent plasma conditions.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Min, K and Lamb, HH and Hauser, JR}, year={2001}, pages={695–700} }
 @article{smith_khandelwal_lamb_2000, title={Ar/N2O remote plasma-assisted oxidation of Si(100): Plasma chemistry, growth kinetics, and interfacial reactions}, volume={18}, ISSN={["1071-1023"]}, DOI={10.1116/1.591467}, abstractNote={The kinetics of Ar/N2O remote plasma-assisted oxidation of Si(100) and the mechanism of nitrogen incorporation at the Si–SiO2 interface were investigated using mass spectrometry, optical emission spectroscopy, and on-line Auger electron spectroscopy. N2, O2, and NO are the stable products of N2O dissociation in the plasma. The maximum NO partial pressure occurs at 10 W applied rf power; N2 and O2 are the predominant products for applied powers greater than 50 W. Ar/N2O remote plasmas are prolific sources of atomic O; in contrast, atomic N is not produced in significant concentrations. Ar/N2O remote plasma-assisted oxidation was investigated at 300 °C for applied rf powers of 5, 20, and 50 W. The oxide growth kinetics are slower than expected for a purely diffusionally controlled process. A diffusion-reaction model that incorporates first-order loss of the oxidizing species as it diffuses through the growing oxide layer fits the data very well. The initial oxidation rate increases linearly with plasma density, suggesting that the near-surface concentration of oxidizing species scales with the surface flux of plasma electrons. Nitrogen is incorporated at the Si–SiO2 interface in direct proportion to the N2 partial pressure in the Ar/N2O remote plasma. Molecular NO does not react at the Si–SiO2 interface at 300 °C, its role in Si thermal oxynitridation notwithstanding. Nitrogen incorporation at the Si–SiO2 interface was also achieved by exposure of ultrathin Ar/O2 plasma oxides to a remote 20 W Ar/N2 plasma.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Smith, BC and Khandelwal, A and Lamb, HH}, year={2000}, pages={1757–1763} }
 @article{lai_lamb_2000, title={Tungsten chemical vapor deposition using tungsten hexacarbonyl: microstructure of as-deposited and annealed films}, volume={370}, ISSN={["0040-6090"]}, DOI={10.1016/S0040-6090(00)00943-3}, abstractNote={Tungsten (W) films were deposited on Si(100) from tungsten hexacarbonyl, [W(CO)6], by low-pressure chemical vapor deposition (CVD) in an ultra-high vacuum (UHV)-compatible reactor. The chemical purity, resistivity, crystallographic phase, and morphology of the deposited films depend markedly on the substrate temperature. Films deposited at 375°C contain approximately 80 at.% tungsten, 15 at.% carbon and 5 at.% oxygen. These films are polycrystalline β-W with a strong (211) orientation and resistivities of >1000 μΩ cm. Vacuum annealing at 900°C converts the metastable β-W to polycrystalline α-W, with a resistivity of approximately 19 μΩ cm. The resultant α-W films are porous, with small randomly oriented grains and nanoscale (<100 nm) voids. Films deposited at 540°C are high-purity (>95 at.%) polycrystalline α-W, with low resistivities (18–23 μΩ cm) and a tendency towards a (100) orientation. Vacuum annealing at 900°C reduces the resistivity to approximately 10 μΩ cm, and results in a columnar morphology with a very strong (100) orientation.}, number={1-2}, journal={THIN SOLID FILMS}, author={Lai, KK and Lamb, HH}, year={2000}, month={Jul}, pages={114–121} }
 @article{reifsnyder_lamb_1999, title={Characterization of silica-supported Pd-Au clusters by X-ray absorption spectroscopy}, volume={103}, ISSN={["1089-5647"]}, DOI={10.1021/jp982893b}, abstractNote={Silica-supported Pd−Au clusters were characterized by Pd K and Au L3 extended X-ray absorption fine structure (EXAFS) spectroscopy and Au L2,3 X-ray absorption near-edge structure (XANES) spectroscopy. Pd−Au/SiO2 catalysts with Pd/Au atomic ratios of approximately 1:1 were prepared by coadsorption of [Pd(NH3)4][NO3]2 and [Au(en)2]Cl3 (en = ethylenediamine) onto silica gel from pH 7 and pH 10 slurries. EXAFS spectroscopy of the Pd−Au/SiO2 (1.3:1, pH 7) catalyst after in situ reduction at 300 °C indicates the formation of bimetallic clusters exhibiting Pd surface enrichment. The EXAFS results can be approximated using a cluster “decoration” model in which a Au-rich core is covered by a partial monolayer of Pd. In contrast, EXAFS spectroscopy of the Pd−Au/SiO2 (1:1, pH 10) catalyst after in situ reduction at 350 °C indicates the formation of homogeneous Pd−Au alloy clusters. The homonuclear bond distances in these clusters agree closely with the Vegard's Law prediction for a 1:1 Pd−Au alloy; however, the het...}, number={2}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Reifsnyder, SN and Lamb, HH}, year={1999}, month={Jan}, pages={321–329} }
 @article{reifsnyder_otten_lamb_1998, title={Nucleation and growth of Pd clusters in mordenite}, volume={39}, ISSN={["0920-5861"]}, DOI={10.1016/S0920-5861(97)00121-1}, abstractNote={The nucleation and growth of Pd clusters in mordenite were investigated using in situ extended X-ray absorption fine structure (EXAFS) spectroscopy and Fourier transform infrared (FTIR) spectroscopy of adsorbed CO. Calcination of [Pd(NH3)4]2+-exchanged mordenite at 350°C in O2 results in decomposition of the amine complex and formation of square-planar Pd2+ oxo species within the mordenite pores. Reduction of these species at 150°C in H2 yields Pd clusters with an average nuclearity of 3. On an average two 2.22 Å Pd–O bonds are associated with each Pd3 cluster; we infer that this interaction serves to anchor the clusters within the pores. After reduction at 150°C, the FTIR spectrum of irreversibly adsorbed CO is indicative of a mixture of Pd+, Pdδ+, and Pd0 carbonyl species. Reduction at 350°C produces larger intrazeolitic Pd clusters (average nuclearity of 6) that exhibit only a weak interaction with the mordenite, as evidenced by their facile aggregation in the presence of CO at 30°C. Reduction at 450°C yields large 20 Å Pd clusters that we infer are located on external mordenite surfaces or locally disrupt the intracrystalline structure.}, number={4}, journal={CATALYSIS TODAY}, author={Reifsnyder, SN and Otten, MM and Lamb, HH}, year={1998}, month={Mar}, pages={317–328} }
 @article{smith_read_yang_srinivasan_courtney_lamb_parsons_1998, title={Plasma enhanced selective area microcrystalline silicon deposition on hydrogenated amorphous silicon: Surface modification for controlled nucleation}, volume={16}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000074150400079&KeyUID=WOS:000074150400079}, DOI={10.1116/1.581144}, abstractNote={Selective deposition of μc-Si on hydrogenated amorphous silicon is demonstrated using time-modulated silane reactant flow in a low temperature plasma enhanced process. Alternating cycles of thin silicon layer deposition and atomic hydrogen exposure result in silicon layers on receptive surfaces, with no net deposition on nonreceptive areas of the substrate. Selective deposition could be useful to form self-aligned contacts in hydrogenated amorphous silicon (a-Si:H transistor applications. However, a problem commonly observed in low temperature selective deposition is that the selective process tends to etch amorphous silicon, harming the devices. We describe a technique involving Mo metallization that stabilizes the a-Si:H surface with respect to hydrogen plasma exposure and allows selective μc-Si deposition on a-Si:H in device structures, while avoiding deposition on the top SiNx insulator material. Surfaces and subsequent selective nucleation and growth were characterized using atomic force microscopy, x-ray photoelectron spectroscopy, and Auger electron spectroscopy, which revealed the presence of Mo incorporation in the a-Si:H surface remaining after complete removal of the metal layer. A direct comparison of selective deposition experiments on films prepared with and without Mo treatment demonstrate that the metallization stabilizes nucleation of microcrystalline silicon on amorphous silicon surfaces.}, number={3}, journal={Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films}, author={Smith, LL and Read, WW and Yang, CS and Srinivasan, E and Courtney, CH and Lamb, HH and Parsons, Gregory}, year={1998}, pages={1316–1320} }
 @article{courtney_smith_lamb_1998, title={Remote plasma-enhanced chemical vapor deposition of SiO2 using Ar/N2O and SiH4}, volume={145}, ISSN={["0013-4651"]}, DOI={10.1149/1.1838898}, abstractNote={Remote plasma-enhanced chemical vapor deposition of SiO 2 using a radio-frequency (rf) Ar/N 2 O plasma and downstream-injected SiH 4 was investigated. The deposition rate at 20 W rf power was measured as a function of pressure, temperature, and SiH 4 flow rate. The SiO 2 deposition rate at 300°C and 300 mTorr depends linearly on the SiH 4 flow rate. The deposition rate is independent of N 2 O flow rate for N 2 O/SiH 4 ratios much greater than 1, consistent with oxygen saturation of the growth surface. The deposition rate increases linearly with pressure up to 400 mTorr. A plateau in the deposition rate is observed above 400 mTorr, and is ascribed to the onset of parasitic gas-phase reactions leading to particle formation. Negative apparent activation energies are observed at pressures ≤400 mTorr, suggesting that adsorption of Si-bearing species is the rate-limiting step in SiO 2 deposition. The deposition chemistry was probed using real-time quadrupole mass spectrometry (QMS) and optical emission spectroscopy (OES). The H 2 + and H 2 O + QMS signal intensities increase monotonically with SiH 4 flow rate; approximately 0.67 moles of H 2 and 1.33 moles of H 2 O are produced per mole of SiH 4 consumed. OES evidences the presence of Ar metastables, N 2 metastables, excited NO molecules, and atomic O in the plasma. Fourier transform infrared spectroscopy of thick SiO 2 films demonstrated that Si-H and Si-OH groups are present at very low concentrations (<1 atom %). Single-wavelength ellipsometry indicated that films deposited under typical O-rich conditions have an average refractive index of 1.464.}, number={11}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Courtney, CH and Smith, BC and Lamb, HH}, year={1998}, month={Nov}, pages={3957–3962} }
 @article{smith_lamb_1998, title={Ultrathin silicon oxynitride films grown by Ar/N2O remote plasma processing}, volume={83}, ISSN={["0021-8979"]}, DOI={10.1063/1.367881}, abstractNote={On-line Auger electron spectroscopy, secondary ion mass spectroscopy, and angle-resolved x-ray photoelectron spectroscopy (ARXPS) were employed to determine the concentration, spatial distribution, and local chemical bonding of nitrogen in ultrathin oxynitride films grown by Ar/N2O remote plasma processing. Nitrogen incorporation in the films occurs primarily at the Si–SiO2 interface irrespective of rf power (5–50 W); however, the interfacial nitrogen concentration increases with rf power. Up to 0.6 monolayers of nitrogen atoms, bonded as (Si–)3N, are incorporated at the interface. Atomic oxygen generated in N2O plasma decomposition scavenges nitrogen from the bulk of the film, effectively confining nitrogen to a very narrow region near the substrate. A very small concentration of nitrogen, bonded as (Si–)2N–O, is detected on the top surface of the film by ARXPS.}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={Smith, BC and Lamb, HH}, year={1998}, month={Jun}, pages={7635–7639} }
 @article{reifsnyder_otten_sayers_lamb_1997, title={Hydrogen chemisorption on silica-supported Pt clusters: In situ X-ray absorption spectroscopy}, volume={101}, ISSN={["1089-5647"]}, DOI={10.1021/jp970244e}, abstractNote={Hydrogen chemisorption on small silica-supported Pt clusters was investigated using in situ extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near-edge structure (XANES) spectroscopy. The clusters were found to exhibit a bulklike Pt first nearest neighbor (NN) distance (2.76 A) and low disorder while covered by chemisorbed hydrogen. In contrast, bare Pt clusters produced by heating in vacuo at 300 °C are characterized by a contracted Pt NN distance (2.66 A) and greater disorder. These effects are reversed by re-exposure of the bare Pt clusters to H2 at 25 °C. The metal−support interface is characterized by a short Pt−O distance, irrespective of the presence of chemisorbed hydrogen. An apparent L3 edge shift of 0.8 eV relative to bulk Pt is observed for the hydrogen-covered clusters. This shift is attributed to a decrease in the Pt L3 edge resonance (white line) intensity, as no corresponding shift is observed at the L2 edge. A hydrogen-related L2,3 XANES feature at 9 eV ap...}, number={25}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Reifsnyder, SN and Otten, MM and Sayers, DE and Lamb, HH}, year={1997}, month={Jun}, pages={4972–4977} }
 @article{reifsnyder_lamb_1996, title={Pd/silica cluster catalysts: Synthesis and reactivity with H-2 and C2H4}, volume={40}, ISSN={["1011-372X"]}, DOI={10.1007/bf00815276}, number={3-4}, journal={CATALYSIS LETTERS}, author={Reifsnyder, SN and Lamb, HH}, year={1996}, pages={155–161} }
 @article{roberts_lamb_1996, title={The effect of reversibility on the selectivity of parallel reactions in a porous catalyst}, volume={51}, ISSN={["0009-2509"]}, DOI={10.1016/0009-2509(95)00266-9}, abstractNote={The selectivity of two first-order, parallel reactions, one reversible and one irreversible, can be altered substantially by the presence of an intraparticle diffusion resistance. At very large resistances, the relative selectivity approaches an asymptotic limit which depends on the kinetic, transport and thermodynamic parameters of the reaction system. It is possible for the selectivity to the product of the reversible reaction to change sign as the pore diffusion resistance increases, i.e. there can be a net formation of that product at low resistances and a net consumption at high resistances. In some cases, the rate of consumption of the product of the reversible reaction can be so high that the ratio of product concentration to reactant concentration in the bulk fluid moves away from the equilibrium ratio. This behavior contrasts markedly with that of two irreversible, first-order reactions in parallel, where the selectivity is independent of the intraparticle diffusion resistance.}, number={3}, journal={CHEMICAL ENGINEERING SCIENCE}, author={Roberts, GW and Lamb, HH}, year={1996}, month={Feb}, pages={441–448} }
 @article{wan_liu_lamb_1995, title={ELECTRON CYCLOTRON-RESONANCE PLASMA REACTOR FOR SIO2 ETCHING - PROCESS DIAGNOSTICS, END-POINT DETECTION, AND SURFACE CHARACTERIZATION}, volume={13}, ISSN={["0734-2101"]}, DOI={10.1116/1.579649}, abstractNote={An electron cyclotron resonance plasma reactor for low-pressure etching of SiO2 layers on Si is described. Under typical operating conditions of 1.1 mTorr neutral pressure, 5 sccm CF4/46 sccm He, and 400 W net microwave power, an average etch rate of 35–40 nm/min is obtained. Ion densities were measured by using a quadrupole mass analyzer (QMA) immersed in the downstream plasma; an optical multichannel analyzer was used for actinometric measurements of atomic F and O concentrations. The results are correlated with process variables and SiO2 etch rates. Real-time end-point detection was effected by actinometry and by monitoring the concentrations of etch products using a differentially pumped QMA. H2 addition inhibits SiO2 etching but improves SiO2/Si etch selectivity. For selective etching, in situ, off-line surface analysis by Auger electron spectroscopy demonstrated an increase in the surface C concentration during SiO2 etching and deposition of a fluorocarbon layer at the end point which strongly inhibits Si etching.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={WAN, ZM and LIU, J and LAMB, HH}, year={1995}, pages={2035–2043} }
 @article{roberts_lamb_1995, title={FALSIFICATION OF ACTIVATION-ENERGIES BY PORE DIFFUSION IN PARALLEL REACTION NETWORKS}, volume={154}, ISSN={["0021-9517"]}, DOI={10.1006/jcat.1995.1178}, abstractNote={The effect of pore diffusion on the behavior of a slow, irreversible reaction that takes place in parallel with a fast, reversible reaction has been analyzed for the case where the reactions are first order in a common reactant. When the resistance to pore diffusion is significant, the apparent activation energy of the slow reaction generally is not equal to one-half of the true activation energy. Rather, the difference between the true and apparent activation energies of the slow reaction depends on the equilibrium constant and on the enthalpy change of the fast, reversible reaction. If the equilibrium constant is small compared to one, or if the enthalpy change of the fast, reversible reaction is close to zero, a significant resistance to pore diffusion will not cause a falsification of the activation energy of the slow reaction. The true activation energy will be observed in these situations. However, if the equilibrium constant of the reversible reaction is large compared to one and if the enthalpy change of this reaction is large, the observed activation energy for the slow, irreversible reaction in the presence of a significant pore diffusion resistance can range from negative for an endothermic reaction to much greater than the true activation energy for an exothermic reaction. The analysis is applied to recent data on the skeletal isomerization and parallel cracking of n-hexane.}, number={2}, journal={JOURNAL OF CATALYSIS}, author={ROBERTS, GW and LAMB, HH}, year={1995}, month={Jul}, pages={364–370} }
 @article{otten_reifsnyder_lamb_1995, title={IN-SITU X-RAY-ABSORPTION SPECTROSCOPY STUDIES OF PT-MORDENITE CATALYSTS}, volume={208}, ISSN={["0921-4526"]}, DOI={10.1016/0921-4526(94)00777-s}, abstractNote={Pt-mordenite catalysts were characterized by in situ EXAFS spectroscopy and H2 temperature-programmed desorption. The results are consistent with the presence of small intracrystalline Pt clusters. Moreover, the EXAFS data evidence PtAl (or Si) bonding following reduction at 450°C in H2.}, number={1-4}, journal={PHYSICA B}, author={OTTEN, MM and REIFSNYDER, SN and LAMB, HH}, year={1995}, month={Mar}, pages={651–652} }
 @article{lai_lamb_1995, title={Precursors for organometallic chemical vapor deposition of tungsten carbide films}, volume={7}, ISSN={["0897-4756"]}, DOI={10.1021/cm00060a016}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPrecursors for Organometallic Chemical Vapor Deposition of Tungsten Carbide FilmsKen K. Lai and H. Henry LambCite this: Chem. Mater. 1995, 7, 12, 2284–2292Publication Date (Print):December 1, 1995Publication History Published online1 May 2002Published inissue 1 December 1995https://doi.org/10.1021/cm00060a016Request reuse permissions Article Views454Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alertsclose Get e-Alerts}, number={12}, journal={CHEMISTRY OF MATERIALS}, author={Lai, KK and Lamb, HH}, year={1995}, month={Dec}, pages={2284–2292} }
 @article{otten_lamb_1994, title={C-BONDED AND O-BONDED CARBON-MONOXIDE ON SURFACES - INTERACTIONS OF [CPW(CO)(3)](-) WITH CATIONS ON MAGNESIA, ALUMINA, AND POTASSIUM-MODIFIED ALUMINA}, volume={116}, ISSN={["0002-7863"]}, DOI={10.1021/ja00083a024}, abstractNote={Surface-bound [CpW(CO)[sub 3]][sup [minus]] complexes were prepared by deprotonation of [HCpW(CO)[sub 3]] on MgO, [gamma]-Al[sub 2]O[sub 3], and K/Al[sub 2]O[sub 3] and characterized by infrared and extended X-ray absorption fine structure (EXAFS) spectroscopies. On the metal oxide surfaces, [CpW(CO)[sub 3]][sup [minus]] interacts with coordinatively unsaturated cations via C- and O-bonded carbonyl ligands. A carbonyl O atom can be envisaged as completing the coordination sphere of a (M[sup n+]) ion terminating the bulk metal oxide. Ion adducts containing one [Sigma]-CO- ligand per complex are formed on each metal oxide; this parallels the solution ion-pair chemistry of [CpW(CO)[sub 3]][sup [minus]] with K[sup +], Mg[sup 2+], and Al[sup 3+]. On highly dehydroxylated MgO and [gamma]-Al[sub 2]O[sub 3], novel bis(isocarbonyl) adducts are formed in which the [CpW(CO)[sub 3]] moiety is inferred to bridge (M[sup n+]) ions via [Sigma]-CO-ligands. The crystallographically characterized compound [(AlMe[sub 2])CpW(CO)[sub 3]][sub 2] is cited as precedent for this bonding geometry in solution organometallic chemistry. 59 refs., 12 figs., 6 tabs.}, number={4}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={OTTEN, MM and LAMB, HH}, year={1994}, month={Feb}, pages={1372–1381} }
 @article{otten_clayton_lamb_1994, title={PLATINUM-MORDENITE CATALYSTS FOR N-HEXANE ISOMERIZATION - CHARACTERIZATION BY X-RAY-ABSORPTION SPECTROSCOPY AND CHEMICAL PROBES}, volume={149}, ISSN={["0021-9517"]}, DOI={10.1006/jcat.1994.1287}, abstractNote={Abstract Platinum-mordenite (Pt-MOR) catalysts were prepared from NH 4 -MOR by ion exchange with [Pt II (NH 3 ) 4 ][OH] 2 , calcination in O 2 at 350°C, and reduction in H 2 at 350°C. The resultant Pt-H-MOR was active for n -hexane isomerization and hydrocracking via bifunctional catalysis at 240-300°C and 1 atm. The observed activation energies for C 6 branched-isomer formation are unusually low, suggesting that the isomerization rates were controlled by pore diffusion. A Pt-KH-MOR catalyst was prepared by ion exchange with aqueous KNO 3 and re-reduction at 350°C; elemental analysis evidenced 90% exchange of protons for K + ions. The product distribution and observed activation energies for C 6 branched-isomer formation over Pt-KH-MOR are consistent with n -hexane isomerization via bifunctional catalysis. Hydrocracking was strongly suppressed, and light hydrocarbons were formed primarily by Pt-catalyzed hydrogenolysis. From in situ extended X-ray absorption fine structure spectroscopy and H 2 temperature-programmed desorption, we conclude that the Pt-MOR catalysts consist of small Pt clusters hosted within the mordenite crystals. The Pt L III X-ray absorption near-edge structure (XANES) spectra of Pt-H-MOR and Pt-KH-MOR are closely similar, suggesting that the electronic structure of the Pt clusters is unaffected by mordenite acid-base chemistry. For the freshly reduced catalysts, a XANES feature at 10 eV relative energy is assigned to Pt-H antibonding states. The infrared spectrum of CO adsorbed on Pt-H-MOR contains an intense band at 2084 cm −1 , which is assigned to linear CO moieties on Pt clusters. A small peak at 2124 cm −1 is assigned to isolated Pt I -CO species, which we infer are formed by oxidative fragmentation of Pt clusters. The infrared spectrum of CO adsorbed on Pt-KH-MOR evidences a red shift of the linear CO band, which we suggest is due to electrostatic interactions between carbonyl O atoms and nearby K + ions.}, number={1}, journal={JOURNAL OF CATALYSIS}, author={OTTEN, MM and CLAYTON, MJ and LAMB, HH}, year={1994}, month={Sep}, pages={211–222} }
 @article{lamb_1993, title={ENGINEERING CATALYST SURFACES WITH METAL-CARBONYL CLUSTERS}, volume={18}, ISSN={["0920-5861"]}, DOI={10.1016/0920-5861(93)80100-f}, abstractNote={This article reviews recent progress in the application of metal carbonyl clusters to preparation of supported catalysts and suggests opportunities for future research. Catalysis by surface-bound metal carbonyl clusters and catalysis by structurally simple supported metals derived by decarbonylation of surface-bound clusters have been achieved. A catalytic cycle for ethene hydrogenation by triosmium clusters on silica has been proposed, and molecular metal clusters have been stabilized on basic metal oxides under conditions of CO hydrogenation catalysis. In these examples, molecular metal clusters are the only organometallic surface species detected by in situ spectroscopy. Surface-bound metal carbonyl clusters have been used to prepare well-defined catalytic entities, ensembles of supported mononuclear complexes and supported metal atom clusters, which retain the nuclearity of the precursor. The latter are structurally simple supported metals which provide an opportunity to explore structure sensitivity in catalysis by nano-scale metal clusters. Of technological importance, metal carbonyl clusters and mononuclear organometallics are being used to engineer multi-layer catalysts with advanced architectures and novel catalytic properties.}, number={1}, journal={CATALYSIS TODAY}, author={LAMB, HH}, year={1993}, month={Oct}, pages={3–19} }
 @article{lamb_gates_1992, title={CHARACTERIZATION OF DECAOSMIUM CARBIDO CARBONYL CLUSTERS SUPPORTED ON MGO}, volume={96}, ISSN={["0022-3654"]}, DOI={10.1021/j100182a016}, abstractNote={Supported decaosmium carbido carbonyl clusters were prepared by surface-mediated organometallic synthesis from chloroosmium complexes on MgO and by adsorption of [Os{sub 10}C(CO){sub 24}]{sup 2-} onto thermally activated MgO from THF solution. The supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy, ultraviolet-visible diffuse reflectance (UV-vis DR) spectroscopy, and infrared spectroscopy. Transmission electron microscope (TEM) images of clusters prepared by surface-mediated synthesis have been obtained. Analysis of the Os L{sub III} EXAFS data indicates that each preparation yields molecularly dispersed {open_quotes}[Os{sub 10}C(CO){sub 24}]{close_quotes} clusters with structures closely similar to that of the dianion in crystalline [Et{sub 4}N]{sub 2}[Os{sub 10}C(CO){sub 24}]. The principal optical absorption of the supported clusters can be assigned to an Os-Os*{yields}CO{open_quotes}2{pi}*{close_quotes} transition by comparison to the UV-vis spectrum of [PPN]{sub 2}[Os{sub 10}C(CO){sub 24}] in solution. Infrared spectra provide evidence of {open_quotes}Os{sub 10}C(CO){sub 24}]{close_quotes} clusters in oxidized and reduced states (relative to the dianion) on the MgO surfaces. Apparently, surface, mediated synthesis yields [Os{sub 10}C(CO){sub 24}]{sup n-}, n = 0, 1, and 2; and adsorption of [Os{sub 10}C(CO){sub 24}]{sup 2-} onto MgO yields [Os{sub 10}C(CO){sub 24}{sup n-}, n = 2, 3, and 4. TEM images of supported clusters prepared by surface-mediated synthesis contain high-contrast scatteringmore » centers about 10 {angstrom} in size that are inferred to be decaosmium species. 32 refs., 7 figs., 3 tabs.« less}, number={3}, journal={JOURNAL OF PHYSICAL CHEMISTRY}, author={LAMB, HH and GATES, BC}, year={1992}, month={Feb}, pages={1099–1105} }
 @article{otten_lamb_1992, title={INFLUENCE OF THE SUPPORT ON THE THERMAL-STABILITY OF SURFACE-BOUND [WCP(CO)3]- - IMPLICATIONS FOR CATALYST DESIGN}, volume={74}, ISSN={["0304-5102"]}, DOI={10.1016/0304-5102(92)80248-f}, abstractNote={Abstract Surface-bound {Mn+}[WCp(CO)3]− complexes on γ-Al2O3 and K-modified Al2O3 were studied by temperature-programmed decomposition (TPDE) andin situ infrared spectroscopy. [WCp(CO)3]− on γ-Al2O3 is adsorbed at Lewis acid centers via two isobridging carbonyl ligands, and [WCp(CO)3]− on K/Al2O3 is ion paired with {K+} ions via a single isocarbonyl. On γ-Al2O3, the strong ion-pairing interaction leads to labilization of CO and low-temperature decomposition. Activation of [WCp(CO)3]− on γ-Al2O3 at 400 °C in flowing He produces stable, highly active catalysts for propene metathesis. Catalysts derived from [WCp(CO)3]− on γ-Al2O3 have maximum activity at 220 °C and exhibit reversible deactivation at higher temperatures. Catalysts derived from [WCp(CO)3]− on K-modified Al2O3 are less active and less stable, suggesting that the Lewis acid centers are an integral component of the sites responsible for metathesis activity.}, number={1-3}, journal={JOURNAL OF MOLECULAR CATALYSIS}, author={OTTEN, MM and LAMB, HH}, year={1992}, pages={305–316} }
 @article{lamb_wolfer_gates_1990, title={A STRUCTURALLY SIMPLE SUPPORTED METAL CATALYST PREPARED FROM DECAOSMIUM CARBONYL CLUSTERS ON MAGNESIUM-OXIDE}, ISSN={["0022-4936"]}, DOI={10.1039/c39900001296}, abstractNote={[Os10C(CO)24]2– on MgO was used to prepare supported metal clusters that are inferred from EXAFS spectroscopy to retain the nuclearity of ten during catalysis of n-butane hydrogenolysis.}, number={19}, journal={JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS}, author={LAMB, HH and WOLFER, M and GATES, BC}, year={1990}, month={Oct}, pages={1296–1298} }
 @article{gates_lamb_1989, title={SUPPORTED METALS AND SUPPORTED ORGANOMETALLICS}, volume={52}, ISSN={["0304-5102"]}, DOI={10.1016/0304-5102(89)80078-1}, abstractNote={Organometallic chemistry and heterogeneous catalysis are developing into common territory, illustrated by catalysts incorporating structures ranging from mononuclear metal complexes to metal aggregates (crystallites) on metal oxide supports. Reactions of precursors such as metal carbonyls and metal allyls with metal oxide surfaces have been understood on the basis of solution organometallic chemistry combined with functional group chemistry of the supports. The supported species are transformed by processes including reductive carbonylation (whereby metal complexes and salts are converted into metal clusters) and oxidative fragmentation (whereby metal clusters and aggregates are converted into mononuclear metal complexes). Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used in conjunction with other techniques to characterize bonds between mononuclear metal complexes and metal oxide surfaces and also to provide structural information about metal-support interfaces in highly dispersed supported metal aggregates. EXAFS results are also helping to define the limitations of standard methods for estimating surface areas of highly dispersed metals by measurements of chemisorption of H2 and CO. Some supported ‘molecular’ organometallics are structurally and catalytically novel, indicating possibilities for design of surface catalytic sites. Ensembles consisting of three Re complexes on MgO are active for the structure-sensitive cyclopropane hydrogenolysis, whereas a catalyst consisting of the same complexes (evidently isolated on the support surface) is inactive. ‘Molecular’ osmium carbonyl clusters stabilized on the basic MgO surface and in basic zeolites catalyze CO hydrogenation, and 10-atom aggregates of osmium, formed by removal of CO ligands from a ‘molecular’ precursor, are active for n-butane hydrogenolysis. These structurally well-defined catalysts offer good opportunities for understanding metal-support interactions and structure sensitivity in metal catalysis.}, number={1}, journal={JOURNAL OF MOLECULAR CATALYSIS}, author={GATES, BC and LAMB, HH}, year={1989}, month={Jun}, pages={1–18} }
 @article{lamb_fung_tooley_puga_krause_kelley_gates_1989, title={SURFACE-MEDIATED ORGANOMETALLIC SYNTHESIS - PREPARATION OF [OS5C(CO)14]2- AND [OS10C(CO)24]2- ON THE BASIC MAGNESIUM-OXIDE SURFACE}, volume={111}, ISSN={["0002-7863"]}, DOI={10.1021/ja00204a007}, abstractNote={Les complexes [Os 5 C(CO) 14 ] 2− et [Os 10 C(CO) 24 ] 2− sont prepares par reaction du melange CO-H 2 a la surface de [H 2 OsCl 6 ] et [Os 3 (CO) 12 ] adsorbes sur MgO}, number={22}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={LAMB, HH and FUNG, AS and TOOLEY, PA and PUGA, J and KRAUSE, TR and KELLEY, MJ and GATES, BC}, year={1989}, month={Oct}, pages={8367–8373} }
 @article{lamb_hasselbring_dybowski_gates_1989, title={SYNTHESIS AND REACTIVITY OF ANIONIC TETRAOSMIUM CLUSTERS ON HIGHLY DEHYDROXYLATED MGO}, volume={56}, ISSN={["0304-5102"]}, DOI={10.1016/0304-5102(89)80170-1}, abstractNote={The deprotonation of H4Os4(CO)12 on MgO gave the supported clusters [H3Os4(CO)12]− and [H2Os4(CO)12]2. The surface-bound anions were extracted from the support by cation metathesis and characterized in solution by infrared and 1H NMR spectroscopies. The anions on highly dehydroxylated MgO were examined by infrared, 13C MAS NMR and UV-vis spectroscopies. The 13C chemical shifts are consistent with a mixture of [H3Os4(CO)12]− and [H2Os4(CO)12]2− surface species. The v(CO) infrared spectrum of [H3Os4(CO)12]−/MgO suggests a simpler structure than the mixture of C2 and C3v isomers observed in solution. We speculate that the relatively nonpolar environment of the MgO surface strongly favors a nonpolar C3v isomer of [H3Os4(CO)12]− in which the negative charge is delocalized over a face of the Os4 tetrahedron. When water was co-adsorbed on the surface, the v(CO) infrared spectrum of [H3Os4(CO)12]− on MgO was brought into close agreement with that of its soluble analog. After treatment of the supported anions in CO + H2 at 200 °C and 1 atm, [H3Os4(CO)12]− and [H2Os4(CO)12]2− (trace) were the only osmium carbonyl species detected by infrared spectroscopy and extraction of surface-bound anions.}, number={1-3}, journal={JOURNAL OF MOLECULAR CATALYSIS}, author={LAMB, HH and HASSELBRING, LC and DYBOWSKI, C and GATES, BC}, year={1989}, month={Nov}, pages={36–49} }
 @article{lamb_gates_knoezinger_1988, title={Organometallic chemistry on surfaces. Reactivity of metal carbonyl compounds on metal oxides}, volume={100}, number={9}, journal={Angewandte Chemie [International Edition in English]}, author={Lamb, H. H. and Gates, B. C. and Knoezinger, H.}, year={1988}, pages={1162–1180} }
 @misc{hasselbring_lamb_dybowski_gates_rheingold_1987, title={C-13 MAGIC-ANGLE SPINNING NMR INVESTIGATION OF SITE EFFECTS IN CRYSTALLINE OS3(CO)12}, volume={127}, ISSN={["0020-1693"]}, DOI={10.1016/s0020-1693(00)82109-x}, number={2}, journal={INORGANICA CHIMICA ACTA}, author={HASSELBRING, L and LAMB, H and DYBOWSKI, C and GATES, B and RHEINGOLD, A}, year={1987}, month={Mar}, pages={L49–L51} }
 @article{koningsberger_lamb_kirlin_kelly_gates_1986, title={AN EXAFS STUDY OF THE FORMATION OF SMALL METAL AGGREGATES ON MGO USING ORGANOMETALLIC COMPOUNDS AS PRECURSORS}, volume={47}, ISSN={["0302-0738"]}, DOI={10.1051/jphyscol:1986848}, abstractNote={EXAFS measurements were carried out on very small Os and Re metal particles supported on MgO. The metal particles were formed via decompn. and subsequent redn. in H of metal carbonyl clusters.}, number={C-8}, journal={JOURNAL DE PHYSIQUE}, author={KONINGSBERGER, DC and LAMB, HH and KIRLIN, PS and KELLY, MJ and GATES, BC}, year={1986}, month={Dec}, pages={261–264} }
 @article{lamb_gates_1986, title={MOLECULAR ORGANOOSMIUM CHEMISTRY AND CATALYSIS ON THE BASIC MAGNESIUM-OXIDE SURFACE}, volume={108}, ISSN={["0002-7863"]}, DOI={10.1021/ja00261a014}, abstractNote={The complex (H/sub 2/Os(CO)/sub 4/) is deprotonated upon adsorption on the basic surface of magnesia. The resulting (HOs(CO)/sub 4/)/sup -/ is held strongly to the surface by a localized carbonyl-Mg/sup 2 +/ interaction analogous to the contact anion ion pairing observed for (Na)(HOs(CO)/sub 4/) in THF. The surface-bound complex is the precursor of surface species that are catalytically active for CO hydrogenation to give methane and higher hydrocarbons at 275 /sup 0/C and 10 atm. During catalysis, the mononuclear anion is transformed into the stable (H/sub 3/Os/sub 4/(CO)/sub 12/)/sup -/ and (Os/sub 10/C(CO)/sub 24/)/sup 2 -/, which become the only surface species detected by infrared spectroscopy and by extraction of surface-bound anions. The chemistry of the molecular condensation reactions of osmium carbonyls on the basic magnesia surface closely parallels that of osmium carbonyls in basic solution. The tetranuclear osmium cluster is suggested to be involved in the CO hydrogenation catalysis. 51 references, 12 figures, 1 table.}, number={1}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={LAMB, HH and GATES, BC}, year={1986}, month={Jan}, pages={81–89} }
 @article{lamb_krause_gates_1986, title={MOLECULAR OSMIUM AND RUTHENIUM CARBONYL CLUSTERS ON CONVENTIONALLY PREPARED CARBON-MONOXIDE HYDROGENATION CATALYSTS}, ISSN={["0022-4936"]}, DOI={10.1039/c39860000821}, abstractNote={Conventional MgO-supported catalysts prepared by aqueous impregnation of [H2OsCl6] and [RuCl3] are converted under conditions of catalytic hydrogenation of CO into supported molecular clusters, [Os10C(CO)24]2– and [Ru6C(CO)16]2–, respectively.}, number={11}, journal={JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS}, author={LAMB, HH and KRAUSE, TR and GATES, BC}, year={1986}, month={Jun}, pages={821–823} }