An XPS—AES study of gaseous xanthates and related sulfur-containing compounds

Abstract

Core XPS spectra for carbon, oxygen, and sulfur and KLL Auger spectra for sulfur in CH 3OCS 2CH 3, (CH 3OCS 2) 2, CS 2, and OCS have been measured and relaxation shifts determined for the sulfur atoms by combining the S 1 s measurement with the S KLL ( 1 D 2) measurement. Relaxation shifts of the sulfur atoms were also estimated from CNDO results for the neutral and core-ionized molecules using the equivalent cores approximation. The results are in qualitative agreement with the measurements, but exaggerate the relaxation by about 100%. The results show that the bonding of the (CH 3O-) group in the two xanthate compounds is very similar. The ionization energies of the S and -S- atoms within the xanthate molecules differ from each other by 1.5 eV; this difference arises almost entirely from the initial-state charge distribution rather than from final-state relaxation. However, the ionization energies of similarly bonded sulfur atoms are nearly the same. The effect of the oxygen atom on the bonding of the carbon and -S- atoms in the (-CS 2-) group in the xanthate compounds is to increase the (C 1 s-S 2 p 3 2 ) ionization energy difference from the value reported for aliphatic disulfides.