Inner-shell spectroscopy of benzaldehyde, terephthalaldehyde, ethylbenzoate, terephthaloyl chloride and phosgene: models for core excitation of poly(ethylene terephthalate)

Hitchcock, Adam P.; Urquhart, Stephen G.; Rightor, E. G.

doi:10.1021/j100201a015

Cited by 109 publications

(104 citation statements)

References 7 publications

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“…Their characteristic features are summarized in Table 2. The first sharp peak at 285·0 Ϯ 0·1 eV is attributed to the C¼C p* resonance, as in benzene (Hitchcock et al, 1992). The second one, at 287·4 Ϯ 0·1 eV, is assigned to the C-H j* resonance.…”

Section: Characteristic Signature Of Polystyrenementioning

confidence: 91%

Physical and chemical changes in polystyrene during electron irradiation using EELS in the TEM: contribution of the dielectric function

Varlot

Martin²,

Quet³

1998

Journal of Microscopy

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SummaryWe have performed electron energy-loss spectroscopy analysis of polystyrene in the analytical transmission electron microscope in order to evaluate the possibility of obtaining both chemical and dielectric information on the polymer at the submicrometre scale. Irradiation has also been studied, particularly the influence of the specimen temperature on the kinetics of degradation.The main results show that polystyrene is resistant to electron beam with a critical dose of about 10 4 C m ¹2 at 127 K. Spectra could be acquired with doses less than this critical dose. We were thus able to propose an identification of the different chemical bonds of carbon (including the C-H bond), in agreement with previous X-ray absorption near-edge structure experiments. The chemical changes in polystyrene due to severe irradiation damage are also visible in the carbon K-edge near-edge structure.At the same time, we calculated the dielectric function from the low-loss part of the spectra. Interestingly, this part of the spectrum is the most sensitive to irradiation, since great changes can be seen during exposure.Lastly, we propose a degradation process, in agreement with all these results.

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Section: Characteristic Signature Of Polystyrenementioning

confidence: 91%

Physical and chemical changes in polystyrene during electron irradiation using EELS in the TEM: contribution of the dielectric function

Varlot

Martin²,

Quet³

1998

Journal of Microscopy

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“…The procedures used to apply EHMO to core-excitation spectroscopy have been documented in earlier studies of organometallic, [41][42][43] conjugated organic, 44 and polymer analogue molecules. 18,21 Predictions of core-excitation spectra were generated from the EHMO output using the equivalent ionic core virtual orbital model (EICVOM) 45 procedures described previously. 18,43,44 Briefly, a calculation is performed on a singly charged molecule in which the core-excited atom is replaced with the Z + 1 atom; for example, the C 1s spectrum of the ring-substitutional site of DMT (denoted C 1s(C-R)) is derived from the EHMO calculation for singly charged DMT, modified by replacing the substituted ring carbon with a N atom.…”

Section: Computational Proceduresmentioning

confidence: 99%

“…18,21 Predictions of core-excitation spectra were generated from the EHMO output using the equivalent ionic core virtual orbital model (EICVOM) 45 procedures described previously. 18,43,44 Briefly, a calculation is performed on a singly charged molecule in which the core-excited atom is replaced with the Z + 1 atom; for example, the C 1s spectrum of the ring-substitutional site of DMT (denoted C 1s(C-R)) is derived from the EHMO calculation for singly charged DMT, modified by replacing the substituted ring carbon with a N atom. The energies of virtual molecular orbitals (VMO) of this EICVOM species are assumed to be related to the position of the core-excitation spectral lines.…”

Section: Computational Proceduresmentioning

confidence: 99%

“…The basis for the use of small molecule (in this case monomer) species as standards for polymer spectra has been discussed and demonstrated previously. 1,[17][18][19]21 The combination of these techniques to study PET and DMT has helped further elucidate assignments for the spectral features of the polymer and monomer. Extended Hückel (EHMO) calculations of DMT are also used to aid interpretation of transitions in the C 1s near edge region.…”

Section: Introductionmentioning

confidence: 99%

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Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

et al. 1997

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The C 1s and O 1s X-ray absorption spectra of poly(ethylene terephthalate) (PET) have been recorded using transmission, fluorescence, and electron yield detection. The corresponding electron energy loss spectra (EELS) have been recorded in a scanning transmission electron microscope. These results are compared to the C 1s and O 1s spectra of gas phase 1,4-dimethyl terephthalate (the monomer of PET) recorded using EELS. The comparison of monomer and polymer materials in different phases and with different techniques has aided the understanding of the relative strengths and limitations of each technique as well as assisting the spectral interpretation. Good agreement is found in the overall shape and the energies of the spectral features. Relatively minor differences in intensities can be understood in terms of the properties of the individual spectroscopic techniques. The critical dose for radiation damage by 100 keV electrons incident on PET at 100 K is found to be (1.45 ( 0.15) × 10 3 eV nm -3 . In contrast, the critical dose for radiation damage by 302 eV X-rays incident on PET at 300 K is (1.2 ( 0.6) × 10 4 eV nm -3 . A figure of merit involving the product of critical energy dose and spectral efficiency (as expressed by the appropriate G value) is developed. This indicates that, for near-edge studies involving a 20 eV spectral width, there is ∼500-fold advantage of X-ray absorption studies on room temperature PET relative to electron energy loss studies of cooled PET.

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“…26 Above the carbonyl transition C 1s f σ* transitions are assigned in accordance with previous assignments. 7,25 3.1.3. Spectroscopy of the Polyether Component.…”

Section: Distinguishing Urea and Carbamatementioning

confidence: 99%

Near-Edge X-ray Absorption Fine Structure Spectroscopy of MDI and TDI Polyurethane Polymers

et al. 1999

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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 MDIbased 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.

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Inner-shell spectroscopy of benzaldehyde, terephthalaldehyde, ethylbenzoate, terephthaloyl chloride and phosgene: models for core excitation of poly(ethylene terephthalate)

Cited by 109 publications

References 7 publications

Physical and chemical changes in polystyrene during electron irradiation using EELS in the TEM: contribution of the dielectric function

Physical and chemical changes in polystyrene during electron irradiation using EELS in the TEM: contribution of the dielectric function

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

Near-Edge X-ray Absorption Fine Structure Spectroscopy of MDI and TDI Polyurethane Polymers

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