A model for interband electroreflectance in polyvalent nearly-free-electron metals, with application to Pb
The interband contribution to the electroreflectance spectrum of Pb has been calculated with a model based on the optical properties of nearly-free-electron polyvalent metals. For such metals parallel band interband transitions dominate. The modulation arises from the uncertainty in wave vector parallel to the applied electric field, which then is simulated by a decrease in interband relaxation time. The model, although lacking microscopic justification, fits the electroreflectance spectra of Pb obtained at two angles of incidence for each of two polarizations using essentially only two fitting parameters, the depth of the modulated region and the (average) field-induced change in the interband relaxation time in this region. The model should be equally applicable to Mg, Al, In, Ga, and Tl.