Observation of Cyclotron Resonance in Surface-Bound Electrons on Liquid Helium

Abstract

We have observed cyclotron resonance from electrons in two-dimensional states outside liquid helium. Their resonant frequency depends only on the perpendicular component of the applied magnetic field, and their observed mobility is that expected for electrons scattered parallel to the liquid surface in only two dimensions, In a recent Letter, Ostermeier and Schwarz 1 have presented data questioning the existence of image-potential-induced surface states for electrons outside of liquid helium. These states had been predicted for dielectrics generally by Cole and Cohen. 2 They are caused by the potential well formed by the attractive image potential outside a dielectric surface, and the repulsive barrier to electron penetration at the surface. For liquid helium, they are calculated to have a binding energy of 0.68 meV and a spatial extent outside the liquid surface of approximately 100 A. Observation of these states was reported

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

“…1.3 K and low input powers. We pay additional attention to the power dependence of the experimental data, since we found that, at lower powers, the weak power broadening of the linewidth also observed in [3] turns into power narrowing and the extrapolation to zero power input cannot be used.…”

“…+ b Cyclotron resonance (CR) studies in two-dimensional (2D) electron systems such as inversion layers on semiconductor surfaces and electrons bound at the free surface of liquid helium have been of great interest for many years [1,2]. Cyclotron resonance serves as a powerful probe for the effects of quantization of both out-of-plane and in-plane (orbital) motions on electron transport phenomena [3,4]. Two-dimensional electrons on a liquid helium surface are usually under extremely strong coupling conditions with respect to mutual Coulomb interaction: e 2 p pn s ͞k B T ¿ 1 (here n s is the electron density).…”

Electrons above a helium surface and the one-dimensional Rydberg atom

“…This phenomena has been observed [6]- [8]. (See [9] for a current review and [10] for a proposed application to quantum computing.…”

Theory of Nondegenerate Two‐Dimensional Electrons Interacting with Phonons in Quantizing Magnetic Fields

“…When the two-dimensional gas is inserted into a transverse magnetic field H the energy spectrum of the carriers (for the sake of concreteness we shall consider electrons) is transformed into a set of discrete Landau levels. Optical absorption due to the transitions of electrons between these levels (cyclotron resonance) was observed in the liquid He-gaseous He interface [3] and in the inversion layer of p-type Si [4 to 61.…”