Core excitation spectra of selected small molecule analogue species have been acquired to assist interpretation of the core excitation spectra of model methylenediphenyldiisocyanate (MDI) polyurethane polymers. Oscillator strength spectra for C ls and 0 ls core excitation of diethyl ether and diisopropyl ether; C ls, N ls, and 0 ls core excitation of urea, N-phenyl urea, N.N1-diphenyl urea, ethyl carbamate, N-phenyl carbamate, N-phenyl N-methyl carbamate, and benzyl carbamate have been derived from gas phase electron energy loss spectra (EELS). Extended Hückel Molecular Orbital (EHMO) calculations are used to assist assignment and to interpret the effect of p-electron delocalization on the gas phase spectra. Functional group identification by core excitation is explored for the purpose of using core excitation spectra for microanalysis of polyurethane polymers.
Keywords: polyurethanes · core excitation
spectroscopy · NEXAFS · EELS · EHMO · molecular
models of polymer subunits
©1995 John Wiley & Sons, Inc.