Dynamical screening of a confined atom by a fullerene

In this paper, we elucidate the role of dynamical screening in the photoionization or photoabsorption process of an atom, which is either confined within a fullerene shell or is adsorbed onto its surface. This effect is of a general nature. Thus, it will also appear for impurity atoms or molecules embedded into or attached onto a metallic cluster. We present a formalism which takes dynamical screening into account. A dynamical screening factor is defined, and is shown to lead to an enhancement of the amplitude of the electromagnetic wave within a specific range of frequencies. This range is determined by the characteristics of the fullerene plasmon (or, more generally, by the plasmon of the confining system).