Optical and Photoemissive Properties of Palladium in the Vacuum Ultraviolet Spectral Region

Abstract

Measurements of the optical properties of evaporated films of Pd for the spectral region from 2 to 24 eV are reported for films prepared and studied in a vacuum of ${10}^{\ensuremath{-}8}$ Torr. The results are correlated with the photoemissive properties of similarly prepared samples for photon energies of 10.2 to 22.4 eV. Interband transitions are identified from the optical data at 1.3, 3.6, 15.2, and 20.5 eV. Pronounced peaks appear in the energy-loss function $\ensuremath{-}\mathrm{Im}[\frac{1}{(\ensuremath{\epsilon}+1)}]$ at 7.3 eV and in $\ensuremath{-}\mathrm{Im}(\frac{1}{\ensuremath{\epsilon}})$ at 7.6 eV. Structure in the photoelectron energy-distribution curves is identified, by correlation with the optical data, as being due to the effects of interband transitions and photoelectron excitation of collective electron oscillations. The temporal dependence of the photoelectron energy distribution curves is also studied.