Far-Infrared Absorptivity of Metals

A simple calculation of the far-infrared absorptivity of a strong-coupling metal in the normal state is presented which is valid in the anomalous-skin-effect (ASE) region. The form of the results is compared with that derived by an alternate procedure in a recent letter by the author. A discussion of electron-phonon renormalization effects in the ASE limit is then considered and, in particular, at frequencies below threshold (₃), an effective mass m₏^** is introduced which incorporates these effects.