Calculation of the frequency shift between the absorption coefficient and the imaginary part of the dielectric constant

Abstract

Assuming a lorentzian shape for the imaginary part ϵ 2 of the dielectric constant, in the frame of the so-called rigourous classical dispersion theory, we show that without further approximations the frequency shift of the absorption coefficient relative to ϵ 2 can be calculated as a function of the damping coefficient.