The lattice specific heats of solid hydrogen and deuterium

Abstract
Measurements of the specific heats of solid parahydrogen and orthodeuterium in the temperature range from 2 to 18°K are described. Anomalous contributions arising from orthohydrogen and paradeuterium impurities were minimized by converting the specimens catalytically in the liquid state, but could only be made negligible for hydrogen. The specific heat at constant volume is deduced for each substance, and its temperature variation discussed in terms of a reduced Debye temperature. It is shown that the behaviour of both substances is very similar to that calculated by Leighton (1948) for crystals of f.c.c. structure.