Abstract:
The properties of the minimum energy W of a low-energy free electron in an inert gas are discussed. This quantity is one of the basic characteristics of the electron in problems of the formation of various charged clusters (bubbles or compacts) in low-dimensional electronic states along interfaces. A relation between the energy W and a similar energy W0 determined in the so-called optical approximation, where the energy W0 is proportional to the gas density ng, has been obtained. Comparison makes it possible to determine the ng dependence of the scattering length a0 introduced in the “optical” description of the gaseous medium and to reveal the conditions under which a0(ng) may change sign, which behavior, by definition, is beyond the framework of the optical approximation and is observed experimentally.