Estimate of surfon evaporation time from the liquid helium surface due to the scattering on ripplons

Recently a new type of surface excitations, surfons, has been proposed. Phenomenologically, these excitations can be interpreted as atoms on a surface quantum level. They explain the strong temperature dependence of surface tension coefficient of liquid helium. In the present work we studied theoretically the interaction of these excitations with ripplons, the quanta of surface waves. The lifetime of surfons due to the absorption of a ripplon and subsequent evaporation from the surface was estimated. The obtained surfon lifetime considerably exceeds the inverse surfon energy, substantiating the treatment of surfons as quasiparticles. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4766586]