Optical transitions in the titanium 〈0 0 0 1〉 band structure

Abstract

Optical transitions in the bulk band structure of the titanium in the 〈0001〉 direction have been observed using the photofield emission method. In the photocurrent–voltage characteristic the optical excitations appear as shoulders. From the voltages at which the shoulders occur, final and initial energies are estimated and compared with theory. Measurements were made for s-polarized light and therefore excitations in the bulk are predominant. The results obtained for photon energies hν=1.96, 2.409, 2.497, 2.541 and 2.602eV are compared with the calculated band structure. These experimental results show that the excitations occur only between two bands and the bands should be considerably shifted, and the minimum of the lower band should be about 0.5eV below that calculated. Additionally, excitations from the titanium (0001) face are observed. A single microcrystal of titanium was obtained by evaporation of titanium onto the tungsten tip emitter in ultra-high vacuum.