Low temperature anomaly of heat capacity of CD4 rotors in solid CD4-Kr solution

TL;DR

This study investigates the unusual low-temperature behavior of heat capacity in a Kr-CD4 solid solution, revealing a distinct temperature dependence of rotational heat capacity compared to other solutions and proposing a model to explain it.

Contribution

The paper introduces a new model explaining the anomalous temperature dependence of rotational heat capacity in Kr-CD4 solutions at 13% concentration.

Findings

Distinct temperature dependence of Crot in 13% CD4 solution

Contribution of molecules in different molecular fields to heat capacity

Estimated energy differences between energy levels in various fields

Abstract

The heat capacity of the solid Kr-CD4 (13% CD4) solution has been investigated. It is shown that the temperature dependence of the heat capacity Crot of the rotational subsystem in this solution is radically different from the corresponding dependences in the previously studied Kr-CD4 (1%, 5% CD4) and Kr-CH4 (5-60%) solutions. A model is proposed to explain the observed dependence Crot(T). The experimental results can be described taking into account the contribution to the heat capacity from CD4 molecules that are in weak, medium and strong molecular fields. The mean concentrations and energy differences between the ground and first excited energy levels of the CD4 molecules in these molecular fields have been estimated.