X-ray Photoemission Studies and Bonding in Amorphous Chalcogens.
Interim technical rept.,
NATIONAL BUREAU OF STANDARDS WASHINGTON D C
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Trends in x-ray photoelectron XPS spectra of chalcogens which relate to their bonding are discussed. Valence band spectra of disordered S are reported along with measurements in the same apparatus of amorphous Se and Te. Each chalcogens spectrum has a minimum about 7 eV below EF, between the largely p-derived states nearer EF and the s-derived states. The p states are split into a largely non-bonding level near EF and a bonding peak an energy delta EP below it. The splitting delta EP S, 3.5 eV Se, 2.9 eV Te, 2.2 eV grows with decreasing atomic number, Z, and is found to scale with Paulings bond energies. The s states exhibit an apparent bonding-antibonding splitting which grows with decreasing Z and scales with the increasing overlap of the s orbitals. Although the s states overlap, comparisons with calculated valence levels in the free atom suggest that most of the cohesive energy in the chalcogens is gained by the bonding of the p electrons, with no major contribution from the s electron.
- Atomic and Molecular Physics and Spectroscopy