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

Oscillator strengths for C 1s and O 1s excitation of terephthalaldehyde, benzaldehyde, and ethyl benzoate and C 1s, O 1s and Cl 2p excitation of terephthaloyl chloride and phosgene have been derived from electron energy loss spectra recorded under scattering conditions where electric dipole transitions dominate. Extended Hueckel molecular orbital (EHMO) calculations were used to aid interpretation of the core excitation spectra of these multifunctional organic molecules. The experimental molecular spectra and EHMO calculations were used to estimate the C 1s and O 1s core excitation spectra of poly(ethylene terephthalate) (PET). Comparisons to the C 1s and O 1s energy loss spectra of PET recorded in an electron microscope have demonstrated that gas-phase spectra and theoretical studies of molecular analogues are useful in interpreting the core excitation spectra of polymers. 48 refs., 14 figs., 13 tabs.