Analysis of the Valence X-Ray Photoelectron Spectra of Eight (–CH2–CHR–)n and Two (–CH2–C(CH3)R–)n Polymers by the Semi-Empirical HAM/3 MO Method Using the Trimer Model Molecules H–(–CH2–CHR–)3–H and H–(–CH2–C(CH3)R–)3–H

Abstract

The valence X-ray photoelectron spectra of ten polymers [(–CH₂–CHR–)_n (R = C₆H₅, OCH₃, COCH₃, COOH, COOCH₃, OCOCH₃, CONH₂, C₄H₆NO (N-vinylpyrrolidone)) and (–CH₂–C(CH₃)R–)_n (R = COOCH₃ and CONH₂)] were analyzed by a semi-empirical HAM/3 MO method using trimer model molecules [H–(–CH₂–CHR–)₃–H (R = C₆H₅, OCH₃, COCH₃, COOH, COOCH₃, OCOCH₃, CONH₂, and C₄H₆NO (N-vinylpyrrolidone) and H–(–CH₂–C(CH₃)R–)₃–H (R = COOCH₃ and CONH₂)], respectively. The calculated Al Kα photoelectron spectra were obtained using Gaussian functions of a fixed approximate linewidth (0.10 I_k; I_k = I′_k − ΔW, where I′_k is the vertical ionization potential of each MO and ΔW is an approximate shift to account for the work-function effects. We assumed that ΔW corresponds to the shift that we must apply before we could compare the calculated spectrum for a single model molecule with the observed spectrum for the solid. The theoretical spectra showed good agreement with the spectra of the polymers, as observed between 0—40 eV.