Cl-LII,III fluorescent x-ray spectra measurement and analysis for the molecular orbital structure of ClO4−, ClO3−, and ClO2−

Abstract

The chlorine LII, III low energy x-ray spectra from sodium perchlorate, chlorate and chlorite have been obtained using carbon Kα (277 eV) photon excitation and a lead myristate analyzing ’’crystal’’ (2d=80 A). X-ray induced decomposition was observed for each of these compounds. By taking repeated spectral scans, systematically distributed over six samples, it was possible to extrapolate to ’’zero-dose’’ Cl-LII, III spectra. A specially developed least-squares fitting program was applied to precisely determine the energy and strength of each spectral component which utilized the known collimation and crystal broadening functions and yielded energy resolutions of less than 1 eV. Broad low-energy satellite structures were observed for all the oxy-anions and for chloride (NaCl) and have been compared to similar satellites as measured in the Ar-LII, III spectrum. These structures were thus identified as resulting from multielectron processes. The other peaks in the Cl-LII, III spectra of the oxy-anions could be understood as corresponding to transitions from molecular orbitals with Cl 3s or 3d character. These results have demonstrated that 3d orbitals do play a definite role in the formation of chemical bonds in the oxy-anions of chlorine and that the importance of this role increases with the oxidation state of the chlorine. Satisfactory correlations have been obtained with the complementary Kβ x-ray emission and photoelectron spectra and with molecular orbital theory for the same anions.