VARIABLE PHOTON ENERGY PHOTOELECTRON SPECTROSCOPIC AND THEORETICAL INVESTIGATIONS OF THE ELECTRONIC-STRUCTURE OF TICL4

The photoelectron spectrum of TiCl4 has been measured using synchrotron radiation over the incident photon energy range 17-69 eV, and relative partial photoionization cross sections have been derived for the valence bands. Band A (1t(1)(-1)) and band B (3t(2)(-1)) display cross section variations typical of Cl 3p atomic orbital-localized levels. Bands C+D show cross section enhancement between 40 and 60 eV and are assigned to 1e(-1) and 2t(2)(-1) Band E (2a(1)(-1)) shows no such feature and has cross section behavior which is appreciably different from that of any of the other bands. The small cross section maximum at 40 eV is attributed to a molecular shape resonance. Discrete variational X alpha calculations support this orbital ordering, and quantitative agreement is found between the experimental and calculated ionization energies. Photoionization cross sections were calculated using the multiple-scattering X alpha method. Good agreement was found between experimental and theoretical branching ratios, confirming the assignment and suggesting that the resonances found in the 2t(2) and 2a(1) orbital cross sections are due to multiple scattering from the localized Cl electrons. The minimum in the 3t(2) cross section is associated with the Cooper minimum of the Cl 3p orbital.