Measurements of Chemical Shifts in the Photoelectron Spectra of Arsenic and Bromine Compounds

Abstract

Chemical shifts in the binding energies of electrons in 3d orbitals of bromine and arsenic have been measured by photoelectron spectroscopy, using soft x rays. The bromine salts studied were KBr, KBrO₃, and KBrO₄; the results are compared to corresponding chlorine and iodine salts studied by other workers. For a given increase in oxidation number, the shift (increase) in binding energy of bromine is intermediate to those for chlorine and iodine, chlorine shifts are higher, and iodine shifts are lower. This trend can be qualitatively explained by Hartree-Fock calculations of differences in binding energies for free halogen ions. Chemical shifts for arsenic can be correlated to variations in the effective charges on arsenic caused by different chemical environments. Calculations of the charge were made by considering the partial ionic character of bonds. A demonstration that photoelectron spectroscopy can be used in arsenic pollution problems has been made.