Heat capacity of p-H₂–p-D₂–Ne solid solution: Effect of (p-D₂)Ne clusters

Abstract

The heat capacity of a solid solution of 1% p-D₂ and 0.25% Ne in p-H₂ has been investigated in the interval ΔT = 0.5–4 K. An excess heat capacity ΔCNe of this solution exceeding the heat capacity of the 1% p-D₂ in p-H₂ solution has been detected and analyzed. It is found that below 2 K the dominant contribution to the heat capacity ΔCNe is made by the rotation of the p-D₂ molecules in the (p-D₂)Ne type clusters. The number of (p-D₂)Ne clusters in the solid sample is strongly dependent on the conditions of preparation. The splitting of the J = 1 level of the p-D₂ molecules in the (p-D₂)Ne clusters Δ = 3.2 K is consistent with the theoretical estimate.