Journal of Physical Chemistry, Vol.100, No.50, 19455-19460, 1996
Analysis of X-Ray Photoelectron-Spectra of 8 Polymers by Demon Density-Functional Calculations Using the Model Oligomers
The X-ray photoelectron spectra of eight polymers [(CH2CH2)(n), (CH2CH2NH)(n), (CH2O)(n), (CH2CH2S)(n), (CH(2)CHX)(n), and (CH(2)CX(2))(n) (X = F, Cl)] were analyzed by the deMon density-functional method using the model oligomers. Calculated AIK a valence photoelectron spectra were obtained using Gaussian line shape functions of an approximate Line width (0.10I(k)), where I-k = I-k’ - WD, I-k’ is the vertical ionization potential of each MO, and WD is a shift to account for sample work function, polarization energy, and other effects. The theoretical spectra showed good agreement with the experimental spectra of the polymers between 0 and 40 eV. The core-electron binding energies (CEBEs) of C1s, N1s, O1s, F1s, S2p, and Cl2p of the model oligomers were calculated by unrestricted generalized transition-state models. The difference between the calculated and the experimental CEBEs reflects the trend in WDs of the polymers.
Keywords:VALENCE ENERGY-LEVELS;ELECTRON BINDING-ENERGIES;SEMIEMPIRICAL MO THEORY;LOCAL-DENSITY;POLY(METHYL METHACRYLATE);POLY(VINYL ALCOHOL);XPS SPECTRA;MOLECULES;CORE;APPROXIMATION