Coulomb Narrowing of the Quantum Cyclotron Resonance in a Nondegenerate Two-Dimensional Electron Liquid

Abstract

We have observed a narrowing of the linear cyclotron resonance linewidth with an increase in the density of surface electrons on liquid helium in the electron-vapor atom scattering regime. The effect changes sign at densities ${n}_{s}>1.7\ifmmode\times\else\texttimes\fi{}{10}^{8}{\mathrm{cm}}^{\ensuremath{-}2}$. The data are interpreted as a Coulombic effect on the Landau level width produced by a strong fluctuating electric field.