VIBRATIONAL FINE-STRUCTURE IN THE SI 2P-PHOTOELECTRON SPECTRA OF SIMPLE GASEOUS MOLECULES

The silicon 2p photoelectron spectra of eleven molecules: SiH4, Si(CH3)4, C2H5SiH3, (CH3)2SiH2, (CH3)3SiH, SiF4, SiCl4, (CH3)3SiCl, (CH3)3SiI, Cl2SiH2, and CH3SiF3, have been recorded at high experimental resolution. The spectra all exhibit broadening, and in some cases resolved fine structure resulting from the excitation of vibrations in the core-ionized molecules. Extensive use is made of the equivalent-cores approximation to aid in the interpretation of the observed vibrational structure. Chemical effects on the lifetime of the Si 2p core holes are postulated for the alkyl-silane molecular series and SiF4 based on the linewidths obtained from deconvolutions of the experimental spectra with manifolds of vibrational bands.