The effect of low energy vibrational modes on the Kapitza resistance

It is postulated that low energy vibrational modes could be present at nonideal surfaces. Their effect on the Kapitza resistance is considered. A model structure of two parallel layers of solid and helium has been used. It is shown that the Kapitza conductance is appreciably enhanced even for phonon wavevectors much less than inverse layer thickness. The degree of enhancement over quite a wide range of temperature is approximately (solid density/helium density) 1 2/. The pressure dependence is less than in the Khalatnikov theory and the model also offers a possible explanation for the observed dependence on the Debye temperature.