Optical properties in the far u.v. and electronic structure of indium films

Reports reflectance measurements of indium films between 2.5 and 15 eV. These films are obtained by evaporation in ultra-high vacuum on cooled substrates. Anomalous absorption is observed on unannealed samples, and remains slightly after annealing. The optical constants are determined by Kramers-Kronig analysis of the reflectance data. The optical conductivity sigma and real part of the dielectric constant epsilon 1 are deduced and compared with theoretical results obtained from Ashcroft's theory (1968). The agreement is good up to 9 eV; beyond this energy the effect of d transitions shifts the experimental curve. The energy-loss function peaks at (11.42+or-0.02) eV.