Plasmon excitations in nondegenerate quasi-one-dimensional electron systems

Abstract

The many-body dielectric formalism is applied for the laterally confined nondegenerate electron system over the liquid helium surface. The density-density response function dependent on the wave number and frequency for the multisubband quasi-one-dimensional (Q1D) system is evaluated within the random-phase approximation for arbitrary values of wave number and subband index. The spectra of both intrasubband and intersubband plasmons are obtained in the limit of small wave numbers and low temperatures. The intrasubband plasmon dispersion is almost soundlike and similar to that of intrasubband plasmons in degenerate Q1D systems and in the Q1D electron chain. The intersubband mode is optical-like with frequency close to the one-electron frequency related to the lateral parabolic confinement. Intra- and intersubband magnetoplasmon frequencies are also derived. Our results are compared with recent spectroscopic experiment.