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

Abstract

The silicon 2p photoelectron spectra of eleven molecules: ${\mathrm{SiH}}_4$, Si(${\mathrm{CH}}_3$ ${)}_4$, ${\mathrm{C}}_2$ ${\mathrm{H}}_5$ ${\mathrm{SiH}}_3$, (${\mathrm{CH}}_3$ ${)}_2$ ${\mathrm{SiH}}_2$, (${\mathrm{CH}}_3$ ${)}_3$SiH, ${\mathrm{SiF}}_4$, ${\mathrm{SiCl}}_4$, (${\mathrm{CH}}_3$ ${)}_3$SiCl, (${\mathrm{CH}}_3$ ${)}_3$SiI, ${\mathrm{Cl}}_2$ ${\mathrm{SiH}}_2$, and ${\mathrm{CH}}_3$ ${\mathrm{SiF}}_3$, 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 ${\mathrm{SiF}}_4$ based on the linewidths obtained from deconvolutions of the experimental spectra with manifolds of vibrational bands.