Electrons on Liquid Helium in a Resonator

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.