Ultraviolet photoemission studies of BaF2and BaCl2

Photoemission measurements on evaporated films of Ba${\mathrm{F}}_2$ and Ba${\mathrm{Cl}}_2$ were made at photon energies of 8-27 eV. Spectral quantum yields and energy distributions of photoemitted electrons were measured. The photoelectron spectra show high-density-of-states structures at 2.5±0.2, 5.2±0.2, and 7.5±0.2 eV above the vacuum level for Ba${\mathrm{F}}_2$ and 3.5±0.2 eV above the vacuum level for Ba${\mathrm{Cl}}_2$. The spectra also provide information on the valence-band widths, band thresholds, and the spin-orbit splitting of the ${\mathrm{Ba}}^{++}$ $5p$ core band of Ba${\mathrm{Cl}}_2$. The energy differences between the regions of initial and final high densities of states are compared with the transition energies of certain structures found in the optical and energy-loss spectra of Ba${\mathrm{F}}_2$.