Temperature dependence of the coupled electron-ripplon resonance spectrum of electron crystal over liquid helium

Spectra of coupled electron-ripplon oscillation of two-dimensional (2D) Wigner crystal with the surface electron density n(s)=6.4 x 10(8) cm(-2) (melting temperature of 0.58 K) are measured under conditions of both complete and noncomplete screening of the holding electric field in temperature range 0.08-0.4 K. The frequencies of the resonances are compared with the results of calculation in the frameworks of a self-consistent theory by Monarkha and Shikin. It is shown that the amplitude of the (0,1) resonance mode tends to 0 as temperature reaches the melting temperature. (c) 2004 Elsevier B.V. All rights reserved.