Intersubband plasmons in quasi-one-dimensional electron systems on a liquid helium surface

TL;DR

This paper investigates the collective excitation spectra of a multisubband quasi-one-dimensional electron gas on liquid helium, revealing intersubband plasmon modes, strong coupling effects, and damping phenomena.

Contribution

It introduces a 12-subband model to identify intersubband plasmon modes and analyzes their coupling, shifts, and damping in a finite temperature electron system.

Findings

Identification of multiple intersubband plasmon modes

Observation of strong intersubband coupling and depolarization shifts

Detection of Landau damping causing plasmon gaps at small wavevectors

Abstract

The collective excitation spectra are studied for a multisubband quasi-one-dimensional electron gas on the surface of liquid helium. Different intersubband plasmon modes are identified by calculating the spectral weight function of the electron gas within a 12 subband model. Strong intersubband coupling and depolarization shifts are found. When the plasmon energy is close to the energy differences between two subbands, Landau damping in this finite temperature system leads to plasmon gaps at small wavevectors.