Vibrational fine structure in the Si 2pphotoelectron spectra of simple gaseous molecules

The silicon 2p photoelectron spectra of eleven molecules: SiH₄, Si(CH₃{)}₄$, ${C}₂H₅{SiH}₃$, (${CH}₃)₂{SiH}₂$, (${CH}₃)₃SiH, SiF₄, SiCl₄, (CH₃{)}₃$SiCl, (${CH}₃)₃SiI, Cl₂{SiH}₂$, and ${CH}₃SiF₃, 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.