We have investigated the details of the eigenmode for a resonator containing a two-dimensional electron system (2DES) formed on the surface of liquid helium. We show that anticrossing phenomena occur near the crossing point ω 0 =ω c , where ω 0 is the eigenmode of the resonator and ω c is the cyclotron frequency. The structure of the coupling constant is established. It is a flexible parameter, i.e., sensitive especially to magnetic field and electron density. A finite coupling leads to a perturbation, δω, of the eigenmode of the resonator in presence of the 2DES. Corresponding calculations and measurements of δω are presented. The theory fits the experimental data. The influence of anticrossing on the cyclotron resonance absorption line shape is demonstrated.

An investigation of the microwave absorption for two-dimensional electron systems (2DES) on helium films and in the presence of a cyclotron resonance (CR) magnetic field are presented. Measured data are explained by a recently proposed two-fraction model of the 2DES, which makes the general structure of the microwave absorption understandable. The fraction of localized and free electrons can be precisely determined and its dependence on the thickness of the helium film above the roughness of the underlying solid substrate is understood.

An investigation of the microwave absorption for 2-dimensional electron layers in a resonator cavity are presented. The difference in the eigenmodes of the resonator in case of an empty cavity and in presence of a 2-dimensional electron layer on a helium film within the cavity are calculated. When introducing electrons into the cavity a pronounced frequency dependence is found. The expected shift in the resonance frequency is compared to previous and new data of resonance response measurements.

We present a systematic investigation of the microwave absorption for two-dimensional electron layers on thin helium films and in the presence of a cyclotron resonance (CR) magnetic field. To explain the measured data, a recently proposed two-fraction structure of the electron system is used and here described in detail. Hereby the problem of substrate roughness, usually always present for electrons on thin helium films, is taken into account and it turns out to be an important parameter. Within this model the general structure of the microwave absorption becomes understandable and the fraction of localized and free electrons can be precisely determined. The details of the observed asymmetry and shift of the CR line shape are discussed.

A systematic theoretical investigation of microwave absorption of 2-dimensional electron systems above a thin helium film in the presence of a cyclotron resonance magnetic field is presented. To explain the measured data, a two-fraction structure of the electron system is introduced. One component corresponds to the free electron motion, the second one takes into account electron localization near the potential minimum caused by the roughness of the substrate. Within this model the general dependence of microwave absorption becomes understandable. The details of the observed cyclotron resonance line-shift are discussed.

Electrons floating above liquid helium form an ideal two-dimensional system with an extremely high mobility. However, the mobility can change substantially when decreasing the thickness of the helium film from bulk to a thin film of a few hundred $\AA{}.$ Furthermore it is observed that for certain film thicknesses there is a pronounced dip in the mobility. We present theoretical investigations and measurements concerning this problem. Taking into account the roughness of the substrate, which supports the helium film, we find theoretically a discontinuity in the chemical potential of the electrons which results in a diplike behavior in the electron current and hence in the electron mobility. This scenario is supported by direct measurements of the electron current on substrates with different roughness and at different electron densities.

Two-dimensional mixture of atomic hydrogen and electrons on the surface of superfluid 4He was realized below 0.5 K. Vibrating capacitor electrometer was employed to show that after the electron capture reaction, H+e−→H−, the product, H−, might penetrate into the bulk liquid.

We investigate the growth of highly strained ultrathin CdS/ZnS quantum well structures by molecular-beam epitaxy with an emphasis on structural aspects such as surface morphology of the growing layer and strain relaxation. As shown by quantitative reflection high-energy electron diffraction (RHEED) measurements, no true three-dimensional nucleation of CdS takes place despite the high mismatch relative to the ZnS buffer. Nevertheless, the CdS surface reveals a high density of very small typically monolayer islands, leading to a strong elastic relaxation at the surface. A new RHEED technique is applied to distinguish this elastic deformation from plastic relaxation through misfit dislocations. The critical thickness for the onset of the latter is found to be three monolayers. This result is confirmed by transmission electron microscopy and photoluminescence measurements carried out for further characterization, proving the presented RHEED technique to be reliable.