Restricted Rotation in Polar Gases near the Critical Point

Abstract

David, Hamann and Pearse1, in a recent communication in Nature, attributed the onset in dielectric loss to a fairly sharp transition to restricted rotation in gaseous methyl fluoride at densities somewhat above the critical value. In a subsequent publication2, they claimed added support for this hypothesis by showing that the correlation parameter g of Kirkwood's theory3 of dielectric polarization increases markedly above unity, the value which it would attain in the absence of such restricted rotation. It is the purpose of this communication to point out that the behaviour of g found by David, Hamann and Pearse is the result of an inappropriate method of calculation, and that the dielectric loss observed can be interpreted without any assumption of a sharp transition to a state characterized by restricted rotation.