Optical absorption of Mo-based alloys

Abstract

A study of the optical absorption of Mo-based dilute alloys ($\mathrm{Mo}\mathrm{Re}$, $\mathrm{Mo}\mathrm{Os}$, $\mathrm{Mo}\mathrm{Pt}$) by a sensitive differential technique is presented. The experiment is analyzed for the difference in the optical conductivity between the alloy and pure Mo. The structures observed in the differential optical conductivity are classified into two groups: One is sensitive to impurity species and the other is not. The former structures, which appear in the region of photon energy below 2 eV, are found to behave consistently with the prediction of the rigid-band approximation in the framework of the indirect optical transition model. The latter structures, which lie above 2 eV, are shown to be well described in terms of the change in optical conductivity arising from impurity-induced wave-vector-nonconserving optical absorption processes, on the basis of the electronic band-structure calculation of pure molybdenum.