Surface Effects on Bulk Plasmons

Abstract

We discuss the effects of surfaces on bulk plasma oscillations in a metallic film of thickness $L$. The leading corrections to the plasma frequencies due to the surfaces are proportional to $L^{-1}$. dispersion relation of bulk modes, $\omega ={\omega }_p[1+\alpha (q^2/k_F^2)]$, where the allowed $q$-values are $q^{(n)}=(n\pi /\overline{L})$, $\overline{L}\equiv L-2d_b$, and $d_b$ is a complex length characteristic of the surface (reminiscent of but different from Feibelman's $d_{\perp }$). An explicit expression for $d_b$ is derived. Resonant excitation by an external field, $E_0{e}^{-i\omega t}$, is calculated.

9 pages (postscipt figures NOT included) (RevTeX 3.0)