A5019137551- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Advanced Chemical Physics Studies
- Advanced X-ray Imaging Techniques
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- Advanced Electron Microscopy Techniques and Applications
- Surface and Thin Film Phenomena
- Machine Learning in Materials Science
- Surface Chemistry and Catalysis
- Force Microscopy Techniques and Applications
- Polymer crystallization and properties
- Nuclear Physics and Applications
- Synthesis and characterization of novel inorganic/organometallic compounds
- Mass Spectrometry Techniques and Applications
- Advanced X-ray and CT Imaging
- Atomic and Molecular Physics
- Glass properties and applications
- Electrochemical Analysis and Applications
- Polymer Nanocomposite Synthesis and Irradiation
- Corrosion Behavior and Inhibition
- Fiber-reinforced polymer composites
- Molecular spectroscopy and chirality
- Semiconductor materials and devices
- Ion-surface interactions and analysis
University of Saskatchewan
2013-2023
Canadian Light Source (Canada)
2008-2018
Material Measurement Laboratory
2017
Lawrence Berkeley National Laboratory
1997-2011
University of Tübingen
2011
Okanagan University College
2008-2009
University of British Columbia
2008-2009
North Carolina State University
1997-2003
Dow Chemical (United States)
1999-2002
Brockhouse Institute for Materials Research
1999-2002
Carbonyl core (C 1s, O 1s) → π*CO transitions are distinctive in the near-edge X-ray absorption fine structure (NEXAFS) spectra of species containing carbonyl groups. These features used for chemical microanalysis organic materials using microscopy. We have explored sensitivity these C 1s and NEXAFS a series polymers group range different bonding environments. Ab initio calculations to explain origin observed trends explore effect that orbital interactions on energy features. The differences...
The C 1s and O X-ray absorption spectra of poly(ethylene terephthalate) (PET) have been recorded using transmission, fluorescence, electron yield detection. corresponding energy loss (EELS) in a scanning transmission microscope. These results are compared to the gas phase 1,4-dimethyl terephthalate (the monomer PET) EELS. comparison polymer materials different phases with techniques has aided understanding relative strengths limitations each technique as well assisting spectral...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInner-shell spectroscopy of benzaldehyde, terephthalaldehyde, ethylbenzoate, terephthaloyl chloride and phosgene: models for core excitation poly(ethylene terephthalate)A. P. Hitchcock, S. G. Urquhart, E. RightorCite this: J. Phys. Chem. 1992, 96, 22, 8736–8750Publication Date (Print):October 1, 1992Publication History Published online1 May 2002Published inissue 1 October...
The effects of carbon black and pyrogeneous silica fillers on the interfacial properties a homopolymer [polybutadiene, (PB)] terpolymer [brominated poly(isobutylene-co-p-methylstyrene), (BIMS)] are reported. Neutron reflectivity (NR) was used to study structure. results complemented by scanning transmission X-ray microscopy (STXM) lateral force (LFM), which were probe morphology surface force. Small-angle neutron scattering (SANS) characterize size filler aggregates in elastomers. Our show...
Scanning transmission X-ray microscopy (STXM) and atomic force have been used to study the morphology chemical composition of macrophase-segregated block copolymers in plaque formulations based on water-blown flexible polyurethane foams. Although there has a large body indirect evidence indicating that observed features water-rich foams are due principally urea components, this work provides first direct, spatially resolved spectroscopic proof support hypothesis. The STXM results consistent...
The C 1s X-ray absorption spectra (XAS) of poly(diallyl phthalate), isophthalate), and poly(ethylene terephthalate) (PET) have been recorded using transmission detection. phthalate segments these polymers are isomers with different patterns substitution (ortho, meta, para) the methyl carboxylate groups on phenyl ring. O electron energy loss (EELS) corresponding isomeric monomers, dimethyl phthalate, isophthalate, terephthalate, also in gas phase inelastic scattering under conditions...
A number of tert-butyl-substituted, cyclic, saturated and unsaturated diaminocarbene, diaminosilylene, diaminogermylene compounds were investigated using inner shell electron energy loss spectroscopy (ISEELS) ab initio calculations. These compounds, each which contains a divalent group 14 element (C, Si, Ge), are particular interest since they stable indefinitely, thus, readily accessible for detailed spectroscopic analysis. The C 1s N spectra the hydrogenated tetravalent analogues carbene,...
Abstract Core excitation spectra of selected small molecule analogue species have been acquired to assist interpretation the core model methylenediphenyldiisocyanate (MDI) polyurethane polymers. Oscillator strength for C 1s and O diethyl ether diisopropyl ether; 1s, N urea, ‐phenyl N, ′‐diphenyl ethyl carbamate, ‐methyl benzyl carbamate derived from gas phase electron energy loss (EELS). Extended Hückel Molecular Orbital (EHMO) calculations are used assignment interpret effect π‐electron...
Carbon 1s (C−R) → π*CC electronic transitions originating from the substituent-bonded carbon atom of a benzene ring show distinctive chemical shifts in their near-edge X-ray absorption fine structure (NEXAFS) spectra. We have systematically explored these through ab initio calculations and carefully calibrated experimental data for wide range molecules containing substituted rings. The systematic disparity between calculated transition energies was used to develop semiempirical correction...
Oscillator strengths for C 1s, N and O 1s excitation spectra of aniline, nitrobenzene, the isomeric nitroanilines have been derived from inner-shell electron energy loss spectroscopy recorded under low momentum transfer conditions (> 2.5 keV impact small scattering angle, θ ≤ 2°). Extended Hückel Molecular Orbital (EHMO) calculations carried out within equivalent core analogy are used to aid spectral interpretation. These investigate sensitivity charge interactions in aromatic molecules...
We report on a high-resolution C-K and O-K near-edge x-ray-absorption fine-structure (NEXAFS) study of large aromatic molecules in condensed thin films, namely, anhydrides 1,4,5,8-naphthalene-tetracarboxylic acid dianhydride, 3,4,9,10-perylene-tetracarboxylic benzoperylene-(1,2)-dicarboxylic anhydride, 1,8-naphthalene-dicarboxylic anhydride the quinoic acenaphthenequinone. Due to high-energy resolution third-generation synchrotron source BESSY II we observe differences NEXAFS fine structures...
The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to differences in key chemical components polyurethane polymers is presented. Carbon 1s NEXAFS spectra made from 4,4'-methylene di-p-phenylene isocyanate (MDI) and toluene diisocyanate (TDI) monomers illustrate that there an unambiguous spectroscopic fingerprint for distinguishing between MDI-based TDI-based polymers. MDI TDI polyurea models show the urea carbamate (urethane) linkages these can be distinguished....
We report the visualization and quantitative analysis of cross-link structure in model core/shell hydrogel polymers on microscopic scale, a fully swollen state, using soft X-ray microscopy. The density these materials their or even nanoscopic variation critically influence characteristics, yet is difficult to characterize by conventional methods. By use microscopy, one can investigate state thus directly visualize quantitatively determine scale. Materials that were cross-linked different...
We report additional rich fine structures in high-resolution near-edge x-ray-absorption structure (NEXAFS) spectra of large organic molecules using NTCDA on Ag(111) as an example. These are completely interpreted vibronic coupling to electronic core excitations. The is mode selective; predominantly one couples each excitation. fit results suggest the occurrence a Davydov splitting, first observed for excitons. Morphological differences substantially influence electron-vibron coupling,...
The nature of the linear dichroism in near-edge X-ray absorption fine structure (NEXAFS) spectra n-alkanes is a matter long-standing controversy. Linear carbon 1s → σ*C-C transition has been interpreted within building block model and molecular orbital model, leading to two different descriptions for angular dependence this feature. When used measurement orientation, application these models will lead results. We have explored NEXAFS single crystals n-alkane hexacontane (n-C60H122). An...