X-ray Emission Spectra of Some Carbon-containing Molecules

Abstract

Ab initio molecular orbital calculations for the energy and intensity of X-ray transitions associated with the carbon monoxide, hydrogen cyanide and carbon dioxide molecules have been calculated at the Hartree-Fock level. It is demonstrated that in general the absolute transition probabilities are sensitive to the inclusion of electronic relaxation effects and interatomic transition moment contributions. It is concluded that calculations for molecular X-r!ly emission henomena should be undertaken at least at the multicentre relaxed Hartree-Fock level to achieve a realistic basis for comparison with experiment. Total carbon-K X-ray rates do not show a strong variation with changes in the molecular environment. The total rates are of a similar magnitude to those reported for the atom. The calculated carbon-K fluorescence yield is also similar in both the carbon atom and the CO2 molecule.