High-resolution HeI and HeII photoelectron spectra of the zinc and cadmium dihalide valence bands

We have recorded high-resolution HeI and HeII photoelectron spectra of the valence bands of six MX₂ compounds (M = Zn, Cd: X = Cl, Br, I) in the gas phase. Transition-state Xα SW calculations on all six compounds confirm the assignments. For the first time, we have clearly resolved the spin-orbit splitting of the II_g and II_u states in the bromide and iodide spectra: and calculated Π_u splittings, using a simple MO LCAO model and the D_xh double group, are in very good agreement with the experimental values. The relative intensities of the photoelectron peaks change markedly from HeI to HeII spectra, and Xα SW cross section calculations on ZnCl₂ predict these intensity changes rather well.