Effect of the classical electron Coulomb crystal on interedge magnetoplasmons

Measurements of the linewidths of interedge magnetoplasmons are reported for electrons on liquid helium in a temperature range from 200 to 600 mK and in a magnetic field B=1 T. The linewidths show an abrupt increase at a certain temperature. This temperature changes if the electron density is altered and can be related to the crystallization temperature. At the frequencies used, the effect on conventional edge magnetoplasmons is only very weak