Temperature dependent angle-resolved photoemission study of the valence bands of single crystal iridium

Abstract

Temperature dependent angle-resolved x-ray photoemission valence bands spectra have been obtained from Iridium (111) single crystal using Mg K excitations and emission both normal and non-normal to the surface. The temperature was varied from 120K to 630K and a high angular resolution of ≤ ± 1.1° Was used. These spectra show strong temperature dependence with dramatic changes occurring at 120K. Data obtained at different temperatures are used to deconvolute direct transition (DT) and non-direct transition (NDT) components via Shevchik's model. This model is found not to give full self consistency. The NDT components are different from the density of states and the DT components still include some residual intensity due to NDT. However, the spectral variations of the DT components agree semi-quantitatively with the predictions of a simple bulk DT model assuming free electron final state dispersion and constant matrix elements.