ELECTRONIC TRANSITIONS IN alpha - AND beta -TITANIUM TRICHLORIDE.

Article abstract of DOI:10.1016/0038-1098(83)90929-8

The reflectance spectrum of alpha -TiCl//3 has been investigated in the range of photon energy between 1. 8 and 10. 4 ev. The optical constants have been obtained by a Kramers-Kronig analysis of the near normal incidence reflectance. The absorption spectrum of beta -TiCl//3 crystalline films in the same energy region is presented. The results are interpreted by means of a model containing both localized and one-electron band states. The low energy peaks of alpha - and beta -TiCl//3 (between 2 and 4 ev) are assigned to localized interionic transitions between d states of neighboring Ti ions. The strong bands beyond 4 ev are ascribed to charge transfer and band-to-band transitions. It is suggested that the interband gap between the anion 3p and the cation 4s bands is around 7. 5 ev in alpha -TiCl//3 and 6. 9 ev in beta -TiCl//3.