THE APPLICATION OF PHOTOEMISSION, MOLECULAR-ORBITAL CALCULATIONS, AND MOLECULAR MECHANICS TO THE SILVER-POLY(PARA-PHENYLENE SULFIDE) INTERFACE

The interfacial chemistry between evaporated Ag and poly(p-phenylene sulfide) (PPS) has been investigated with x-ray photoelectron spectroscopy (XPS). The initial stages of nucleation and growth of Ag in the subatomic-layer regime were monitored. The PPS core level spectra exhibit no detectable changes as a function of Ag coverage; however, the Ag 3d5/2 peak position shifts approximately 0.6 eV to higher binding energy at low Ag coverages. At low Ag coverages, the valence band spectra consist of two main features centered at 2.5 and 5.9 eV. Unrestricted Hartree-Fock (UHF) molecular orbital calculations suggest that the 5.9 eV band consists of weakly perturbed Ag 4d orbitals and bonding Ag 4d-S 3p hybrid orbitals. The 2.5 eV band consists of antibonding Ag 4d-S 3p hybrid orbitals. Molecular mechanics results suggest that the sulfur atom transforms from a bent to either a trigonal pyramidal or trigonal planar configuration after bonding with Ag. Both the molecular orbital calculations and molecular mechanics results suggest that the trigonal pyramidal configuration is more favorable.