Realization of the triple points of equilibrium hydrogen by an open cell method using a GM closed-cycle refrigerator

摘要

The triple point of equilibrium hydrogen is realized by an open cell method using a closed-cycle helium refrigerator. Abnormality is observed on the heat capacity curves of solid hydrogen at temperatures of about 0.1 K below the triple point of equilibrium hydrogen in the case of usage of 2 g of activated ferric hydroxide as a catalyst for the ortho- and para-hydrogen's equilibration. No abnormality is, however, observed in the case of 0.2 g of a catalyst against about 0.1 mol of hydrogen. In the latter case, it takes about 3 days for equilibration of ortho- and para-hydrogen and flat melting curves are obtained.