Infrared and optical properties of Na, K, and Rb metals

Abstract

The infrared and optical data on Na, K, and Rb are reanalyzed within the framework of the nearly-free-electron model with interband transitions and are shown to be inconsistent with this model. An intrinsic surface plasmon-assisted absorption process is proposed and the general frequency-dependent properties of this model are found to be consistent with experiment. When a detailed phenomenological description of this scattering process is incorporated into the nearly-free-electron model, the frequency dependences of both the optical conductivity and infrared mass data for solid alkali-metal-dielectric interfaces and of liquid Na are reproduced.