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

The photoelectron spectrum of TiCl4 has been measured using synchrotro n radiation over the incident photon energy range 17-69 eV, and relati ve partial photoionization cross sections have been derived for the va lence bands. Band A (1t(1)(-1)) and band B (3t(2)(-1)) display cross s ection variations typical of Cl 3p atomic orbital-localized levels. Ba nds C+D show cross section enhancement between 40 and 60 eV and are as signed to 1e(-1) and 2t(2)(-1) Band E (2a(1)(-1)) shows no such featur e and has cross section behavior which is appreciably different from t hat of any of the other bands. The small cross section maximum at 40 e V is attributed to a molecular shape resonance. Discrete variational X alpha calculations support this orbital ordering, and quantitative ag reement is found between the experimental and calculated ionization en ergies. Photoionization cross sections were calculated using the multi ple-scattering X alpha method. Good agreement was found between experi mental and theoretical branching ratios, confirming the assignment and suggesting that the resonances found in the 2t(2) and 2a(1) orbital c ross sections are due to multiple scattering from the localized Cl ele ctrons. The minimum in the 3t(2) cross section is associated with the Cooper minimum of the Cl 3p orbital.