Solid hydrogen films in a nonequilibrium state

Abstract

Molecular hydrogen can be prepared as a metastable quantum solid by quench-condensation onto a substrate at sufficiently low temperature. Using surface plasmon resonance and light scattering techniques we have investigated such H 2 films with thicknesses up to several 100A˚, condensed onto a silver surface at 1.5 K. Since solid H 2 does not wet silver these films are in an extreme nonequilibrium state. At a temperature of 2.3 K we observe a dramatic rearrangement of the film overstructure on scales of ∼1 μm, which implies an extremely high mobility of the H 2 molecules at a temperature far below the desorption threshold (3.8 K).