Chemical dependence of core-level linewidths and ligand-field splittings: High-resolution core-level photoelectron spectra of I 4<i>d</i>levels

Abstract

High-resolution I 4d photoelectron spectra (total instrumental resolution 0.06 eV) of several iodine molecules, ICl, IBr, ${\mathrm{I}}_{2}$, and ${\mathrm{Ch}}_{2}$${\mathrm{I}}_{2}$, are reported. The inherent I 4d Lorentzian linewidths increase in the above order, due to the decrease in electronegativity of the moieties bound to I. The ligand-field splitting as measured by the ${\mathit{C}}_{2}^{0}$ crystal-field term decreases in the above order, and correlates extremely well with the electric-field gradient measured by $^{129}\mathrm{I}$ quadrupole splittings.