QUANTUM EVAPORATION FROM QUANTUM LIQUIDS AND SOLIDS

Quantum evaporation is the evaporation of atoms from the surface of a liquid or solid by single excitations, such as phonons. We show that this process can only occur in systems for which the deBoer quantum parameter is above a critical value. For super fluid helium we argue that, because the interface between liquid and gas is not sharp, it may be useful to consider quantum evaporation as a process in which excitations coming from the liquid are adiabatically deformed as they propagate through the interface and then emerge as gas atoms. Based on this picture, we make several predictions which can be tested experimentally. Finally, we discuss quantum evaporation in solid hydrogen.