@article{winesett_ade_smith_urquhart_dias_stevens_2003, title={Application of scanning transmission X-ray microscopy to the rubber industry}, volume={76}, ISSN={["1943-4804"]}, DOI={10.5254/1.3547773}, abstractNote={Abstract}, number={4}, journal={RUBBER CHEMISTRY AND TECHNOLOGY}, author={Winesett, DA and Ade, H and Smith, AP and Urquhart, SG and Dias, AJ and Stevens, P}, year={2003}, pages={803–811} }
 @article{dhez_ade_urquhart_2003, title={Calibrated NEXAFS spectra of some common polymers}, volume={128}, ISSN={["0368-2048"]}, DOI={10.1016/S0368-2048(02)00237-2}, abstractNote={Near edge X-ray absorption fine structure (NEXAFS) microscopy has evolved into a powerful characterization tool for polymeric materials. The foundation of this utility depends crucially on the sensitivity of NEXAFS to the specific chemical structure of the polymer. Furthermore, for quantitative compositional analysis, reliable reference spectra with known energy resolution and calibrated energy scale are required. We report a set of NEXAFS spectra from 24 common polymers that represent a range of chemical functionalities in order to create a database of calibrated polymer NEXAFS spectra to be used for compositional analysis. These spectra illustrate the sensitivity of NEXAFS spectroscopy to the polymer composition, illustrating the potential of NEXAFS for chemical analysis.}, number={1}, journal={JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA}, author={Dhez, O and Ade, H and Urquhart, SG}, year={2003}, month={Jan}, pages={85–96} }
 @article{coffey_urquhart_ade_2002, title={Characterization of the effects of soft X-ray irradiation on polymers}, volume={122}, ISSN={["1873-2526"]}, DOI={10.1016/S0368-2048(01)00342-5}, abstractNote={The physical and chemical effects of the soft X-ray irradiation of polymers have been systematically evaluated for photon energies just above the C 1s binding energy. This exposure causes radiation damage in the form of the loss of mass and changes to the chemical structure of the polymers. These effects are evident in the Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of the exposed polymers, posing a fundamental limit to the sensitivity of NEXAFS spectroscopy for chemical microanalysis. Quantitative understanding of the chemistry and kinetics of radiation damage in polymers is necessary for the successful and validated application of NEXAFS microscopy. This paper outlines a method for quantifying this radiation damage as a function of X-ray dose, and applies these methods to characterize the loss of mass and loss of carbonyl group functionality from a diverse series of polymers. A series of simple correlations are proposed to rationalize the observed radiation damage propensities on the basis of the polymer chemical structure. In addition, NEXAFS spectra of irradiated and virgin polymers are used to provide a first-order identification of the radiation chemistry.}, number={1}, journal={JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA}, author={Coffey, T and Urquhart, SG and Ade, H}, year={2002}, month={Jan}, pages={65–78} }
 @article{rightor_urquhart_hitchcock_ade_smith_mitchell_priester_aneja_appel_wilkes_et al._2002, title={Identification and quantitation of urea precipitates in flexible polyurethane foam formulations by X-ray spectromicroscopy}, volume={35}, ISSN={["1520-5835"]}, DOI={10.1021/ma0122627}, abstractNote={Scanning transmission X-ray microscopy (STXM) and atomic force microscopy have been used to study the morphology and chemical composition of macrophase-segregated block copolymers in plaque formulations based on water-blown flexible polyurethane foams. Although there has been a large body of indirect evidence indicating that the observed macrophase-segregated features in water-rich polyurethane foams are due principally to urea components, this work provides the first direct, spatially resolved spectroscopic proof to support this hypothesis. The STXM results are consistent with a segregation model where urea segments segregate, forming enriched phases with the majority of the polyether- polyol and urethane groups at the chain ends of the urea hard segments. Chemical mapping of the urea, urethane, and polyether distribution about the urea-rich segregated phases showed that the urea concentration changes gradually (across several hundred nanometers) in a butylene oxide-based foam. This mapping also showed the urea-rich segregated phases present as a partial network in an ethylene oxide/propylene oxide sample.}, number={15}, journal={MACROMOLECULES}, author={Rightor, EG and Urquhart, SG and Hitchcock, AP and Ade, H and Smith, AP and Mitchell, GE and Priester, RD and Aneja, A and Appel, G and Wilkes, G and et al.}, year={2002}, month={Jul}, pages={5873–5882} }
 @article{mitchell_wilson_dineen_urquhart_hayes_rightor_hitchcock_ade_2002, title={Quantitative characterization of microscopic variations in the cross-link density of gels}, volume={35}, ISSN={["1520-5835"]}, DOI={10.1021/ma010840d}, abstractNote={We report the visualization and quantitative analysis of the cross-link structure in model core/shell hydrogel polymers on the microscopic scale, in a fully swollen state, using soft X-ray microscopy. The cross-link density in these materials and their microscopic or even nanoscopic variation critically influence materials characteristics, yet the cross-link density is difficult to characterize by conventional methods. By the use of soft X-ray microscopy, one can investigate these materials in a fully swollen state and thus directly visualize and quantitatively determine the cross-link structure on a microscopic scale. Materials that were cross-linked by different methods were shown to give rise to differently shaped profiles. Abrupt and gradient cross-link density profiles have been investigated, and the spatial variation in their cross-link density has been determined quantitatively.}, number={4}, journal={MACROMOLECULES}, author={Mitchell, GE and Wilson, LR and Dineen, MT and Urquhart, SG and Hayes, F and Rightor, EG and Hitchcock, AP and Ade, H}, year={2002}, month={Feb}, pages={1336–1341} }
 @article{zhang_li_tang_ge_hu_rafailovich_sokolov_gersappe_peiffer_li_et al._2001, title={Interfacial properties of elastomer blends as studied by neutron reflectivity}, volume={42}, ISSN={["0032-3861"]}, DOI={10.1016/S0032-3861(01)00370-6}, abstractNote={The interfacial properties of a homopolymer (polybutadiene (PB)) and a terpolymer (brominated poly(isobutylene-co-p-methylstyrene) (BIMS)) are reported. Neutron reflectivity was used to study the interfacial structure. The results were complemented by scanning transmission X-ray microscopy and atomic force microscopy, which were used to probe the morphology of these binary blends. Our results show that the interfacial behavior of these elastomeric blends is a direct function of the BIMS chemical composition. The interfacial width decreased with increasing bromide functionality. At levels below 8 mol%, the para-methylstyrene concentration had a less pronounced effect on the compatibility and interfacial characteristics. We also studied the effect of styrene butadiene random copolymers on the miscibility of the PB/BIMS blends. The results showed that styrene-butadiene rubber (SBR) was not fully miscible with BIMS and PB on an individual basis, but addition of relatively small amount of SBR enhances the compatibilization of the PB/BIMS interface. Self-consistent field (SCF) modeling was used to determine the optimum copolymer composition. The calculations are consistent with the experimental results.}, number={21}, journal={POLYMER}, author={Zhang, YM and Li, W and Tang, B and Ge, S and Hu, X and Rafailovich, MH and Sokolov, JC and Gersappe, D and Peiffer, DG and Li, Z and et al.}, year={2001}, month={Oct}, pages={9133–9141} }
 @article{hitchcock_koprinarov_tyliszczak_rightor_mitchell_dineen_hayes_lidy_priester_urquhart_et al._2001, title={Optimization of scanning transmission X-ray microscopy for the identification and quantitation of reinforcing particles in polyurethanes}, volume={88}, ISSN={["1879-2723"]}, DOI={10.1016/S0304-3991(00)00113-3}, abstractNote={The morphology, size distributions, spatial distributions, and quantitative chemical compositions of co-polymer polyol-reinforcing particles in a polyurethane have been investigated with scanning transmission X-ray microscopy (STXM). A detailed discussion of microscope operating procedures is presented and ways to avoid potential artifacts are discussed. Images at selected photon energies in the C 1s, N 1s and O 1s regions allow unambiguous identification of styrene-acrylonitrile-based (SAN) copolymer and polyisocyanate polyaddition product-based (PIPA) reinforcing particles down to particle sizes at the limit of the spatial resolution (50 nm). Quantitative analysis of the chemical composition of individual reinforcing particles is achieved by fitting C 1s spectra to linear combinations of reference spectra. Regression analyses of sequences of images recorded through the chemically sensitive ranges of the C 1s, N 1s and O 1s spectra are used to generate quantitative compositional maps, which provide a fast and effective means of investigating compositional distributions over a large number of reinforcing particles. The size distribution of all particles determined by STXM is shown to be similar to that determined by TEM. The size distributions of each type of reinforcing particle, which differ considerably, were obtained by analysis of STXM images at chemically selective energies.}, number={1}, journal={ULTRAMICROSCOPY}, author={Hitchcock, AP and Koprinarov, I and Tyliszczak, T and Rightor, EG and Mitchell, GE and Dineen, MT and Hayes, F and Lidy, W and Priester, RD and Urquhart, SG and et al.}, year={2001}, month={Jun}, pages={33–49} }
 @article{smith_urquhart_winesett_mitchell_ade_2001, title={Use of near edge X-ray absorption fine structure spectromicroscopy to characterize multicomponent polymeric systems}, volume={55}, DOI={10.1366/0003702011954008}, abstractNote={ The merits of a polymer characterization technique, near edge X-ray absorption fine structure (NEXAFS) spectromicroscopy, are demonstrated through the characterization of a multilayer polymer film with partially unknown chemical composition. The combination of chemical speciation through NEXAFS spectroscopy with the high spatial resolution available in X-ray microscopy allows the characterization of polymeric materials not possible with conventional techniques. Analysis of a multilayer with layers as thin as 4 μm has yielded results that differ from those previously obtained by infrared microscopy. Layers below the spatial resolution limit of infrared microscopy were characterized. }, number={12}, journal={Applied Spectroscopy}, author={Smith, A. P. and Urquhart, S. G. and Winesett, D. A. and Mitchell, G. and Ade, Harald}, year={2001}, pages={1676–1681} }
 @inbook{mitchell_wilson_rightor_dineen_hayes_urquhart_hitchcock_ade_2000, title={Characterization of microscopic variation in crosslink density in polymer gels using scanning transmission X-ray microscopy}, volume={165}, ISBN={0750306858}, number={2000}, booktitle={Microbeam Analysis 2000: proceedings of the Second Conference of the International Union of Microbeam Analysis Societies held in Kailua-Kona, Hawaii, 9-14 July 2000}, publisher={Bristol: Institute of Physics Publishing}, author={Mitchell, G. and Wilson, L. R. and Rightor, E. G. and Dineen, M. T. and Hayes, F. and Urquhart, S. and Hitchcock, A. and Ade, H.}, editor={Williams, D. B. and Shimizu, R.Editors}, year={2000}, pages={113–114} }
 @article{urquhart_ade_rafailovich_sokolov_zhang_2000, title={Chemical and vibronic effects in the high-resolution near-edge X-ray absorption fine structure spectra of polystyrene isotopomers}, volume={322}, DOI={10.1016/s0009-2614(00)00441-3}, abstractNote={This Letter presents the high-resolution C 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of hydrogenated and deuterated polystyrene. The differences between these spectra provide unambiguous evidence for the presence of a significant vibronic contribution to the shape and structure of the C 1s(C–H) →1π∗CC transition in polystyrene. High-resolution NEXAFS spectra, spectroscopic simulations and ab initio calculations are used to help resolve the relative contributions of chemical shifts and vibronic excitation to the shape of the characteristic C 1s(C–H) →1π∗CC transition.}, number={5}, journal={Chemical Physics Letters}, author={Urquhart, S. G. and Ade, Harald and Rafailovich, M. and Sokolov, J. S. and Zhang, Y.}, year={2000}, pages={412–418} }
 @inbook{rightor_urquhart_hitchcock_ade_mitchell_dineen_hayes_priester_lidy_2000, title={Segregated phases in flexible polyurethanes by x-ray spectromicroscopy}, volume={165}, ISBN={0750306858}, number={2000}, booktitle={Microbeam Analysis 2000: proceedings of the Second Conference of the International Union of Microbeam Analysis Societies held in Kailua-Kona, Hawaii, 9-14 July 2000}, publisher={Bristol: Institute of Physics Publishing}, author={Rightor, E. and Urquhart, S. and Hitchcock, A. and Ade, H. and Mitchell, G. and Dineen, M. T. and Hayes, F. and Priester, R. and Lidy, W.}, editor={Williams, D. B. and Shimizu, R.Editors}, year={2000}, pages={111–112} }
 @article{lehmann_urquhart_ennis_hitchcock_hatano_gupta_denk_1999, title={Core excitation spectroscopy of stable cyclic diaminocarbenes, -silylenes, and -germylenes}, volume={18}, ISSN={["0276-7333"]}, DOI={10.1021/om980882z}, abstractNote={A number of tert-butyl-substituted, cyclic, saturated and unsaturated diaminocarbene, diaminosilylene, and diaminogermylene compounds were investigated using inner shell electron energy loss spectroscopy (ISEELS) and ab initio calculations. These compounds, each of which contains a divalent group 14 element (C, Si, Ge), are of particular interest since they are stable indefinitely, and thus, they are readily accessible for detailed spectroscopic analysis. The C 1s and N 1s spectra of the hydrogenated tetravalent analogues of the saturated carbene, of di-tert-butyldiazabutadiene, and of di-tert-butyldiazabutane were also obtained to assist with spectral interpretation. Our analysis shows that there is significant π-allyl delocalization over the N−EII−N fragment in all three species. Further, in the unsaturated species there is additional aromatic delocalization. Both theory and experiment indicate that the divalent center of the carbene is qualitatively different from that in the germylenes or silylenes.}, number={10}, journal={ORGANOMETALLICS}, author={Lehmann, JF and Urquhart, SG and Ennis, LE and Hitchcock, AP and Hatano, K and Gupta, S and Denk, MK}, year={1999}, month={May}, pages={1862–1872} }
 @article{urquhart_hitchcock_smith_ade_lidy_rightor_mitchell_1999, title={NEXAFS spectromicroscopy of polymers: overview and quantitative analysis of polyurethane polymers}, volume={100}, ISSN={["1873-2526"]}, DOI={10.1016/S0368-2048(99)00043-2}, abstractNote={The successful application of X-ray spectromicroscopy to chemical analysis of polymers is reviewed and a detailed application to quantitative analysis of polyurethanes is presented. Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy is the basis of chemical sensitive X-ray imaging, as well as qualitative and quantitative micro-spectroscopy. These capabilities are demonstrated by a review of recent work, and by presentation of new results outlining a methodology for quantitative speciation of polyurethane polymers. C 1s inner-shell excitation spectra of a series of molecular and polymeric model compounds, recorded by gas phase inelastic electron scattering (ISEELS) and solid phase NEXAFS techniques, are used to understand the spectroscopic basis for chemical analysis of polyurethanes. These model species contain the aromatic urea, aromatic urethane (carbamate) and aliphatic ether functionalities that are the main constituents of polyurethane polymers. Ab initio calculations of several of the model molecular compounds are used to support spectral assignments and give insight into the origin and relative intensities of characteristic spectral features. The model polymer spectra provide reference standards for qualitative identification and quantitative analysis of polyurethane polymers. The chemical compositions of three polyurethane test polymers with systematic variation in urea/urethane content are measured using the spectra of model toluene diisocyanate (TDI) urea, TDI-carbamate, and poly(propylene oxide) polymers as reference standards.}, number={1999 Oct.}, journal={JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA}, author={Urquhart, SG and Hitchcock, AP and Smith, AP and Ade, HW and Lidy, W and Rightor, EG and Mitchell, GE}, year={1999}, month={Oct}, pages={119–135} }
 @article{urquhart_smith_ade_hitchcock_rightor_lidy_1999, title={Near-edge X-ray absorption fine structure spectroscopy of MDI and TDI polyurethane polymers}, volume={103}, ISSN={["1089-5647"]}, DOI={10.1021/jp990059w}, abstractNote={The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to differences in key chemical components of polyurethane polymers is presented. Carbon 1s NEXAFS spectra of polyurethane polymers made from 4,4‘-methylene di-p-phenylene isocyanate (MDI) and toluene diisocyanate (TDI) isocyanate monomers illustrate that there is an unambiguous spectroscopic fingerprint for distinguishing between MDI-based and TDI-based polyurethane polymers. NEXAFS spectra of MDI and TDI polyurea and polyurethane models show that the urea and carbamate (urethane) linkages in these polymers can be distinguished. The NEXAFS spectroscopy of the polyether component of these polymers is discussed, and the differences between the spectra of MDI and TDI polyurethanes synthesized with polyether polyols of different molecular composition and different molecular weight are presented. These polymer spectra reported herein provide appropriate model spectra to represent the pure components for quantitative microanalysis.}, number={22}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Urquhart, SG and Smith, AP and Ade, HW and Hitchcock, AP and Rightor, EG and Lidy, W}, year={1999}, month={Jun}, pages={4603–4610} }
 @article{giebler_schulz_reiche_brehmer_wuhn_woll_smith_urquhart_ade_unger_1999, title={Near-edge X-ray absorption fine structure spectroscopy on ordered films of an amphiphilic derivate of 2,5-diphenyl-1,3,4-oxadiazole}, volume={15}, ISSN={["0743-7463"]}, DOI={10.1021/la980888t}, abstractNote={The surfaces of ordered films formed from an amphiphilic derivative of 2,5-diphenyl-1,3,4-oxadiazole by the Langmuir−Blodgett (LB) technique and organic molecular beam deposition (OMBD) were investigated by the use of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. For the assignment of the spectral features of the C, N, and O K-edge absorption spectra, fingerprint spectra of poly(p-phenylene terephthalamide) (Kevlar), poly(ethylene terephthalate), poly(p-phenylene-1,3,4-oxadiazole), and 2,5-di(pentadecyl)-1,3,4-oxadiazole, which contain related chemical moieties, were recorded. Ab initio molecular orbital calculations, performed with explicit treatment of the core hole, are used to support the spectral interpretations. Angle-resolved NEXAFS spectroscopy at the C, N, and O K-edges suggests a preferentially upright orientation of the oxadiazole derivative in the outermost layer of the films. X-ray specular reflectivity data and molecular modeling results suggest a similar interpretation.}, number={4}, journal={LANGMUIR}, author={Giebler, R and Schulz, B and Reiche, J and Brehmer, L and Wuhn, M and Woll, C and Smith, AP and Urquhart, SG and Ade, HW and Unger, WES}, year={1999}, month={Feb}, pages={1291–1298} }