An investigation of the rotational motion of 14N2 molecules in a solid Ar matrix by a calorimetric method

The specific heat of solid solutions of l4N2 in argon with concentrations n = 0.125, 0.25, 0.50, and 1.02 mole % has been studied in the temperature range 0.5–12° K. It was shown that the characteristic time for conversion of the nitrogen impurity is above 102 hours. Analysis of the temperature dependence of the specific heat showed the limitations of the Devonshire–Manz–Mirsky model and enabled information to be derived about the low-temperature part of the rotational spectrum of an isolated impurity molecule. The concentration dependence of the specific heat of a solution provides evidence in favor of the suggestion of the appreciable role of dynamic interaction between the impurity molecules, brought about through relaxation of the matrix in the surrounding region.