Piezo-rotatory coefficients and stress-induced optical activity

Abstract

This paper reports the methods of obtaining the components of the fourth rank axial piezo-rotatory tensor in different crystal classes. The methods of recovering the two piezo-rotatory coefficients R₁₁ and R₁₂ of isotropic optically active glasses, the three coefficients R₁₁, R₁₂ and R₄₄ of cubic crystals belonging to the point group 432 and the four coefficients R₁₁, R₁₂, R₁₃ and R₄₄ of crystals like NaClO₃ (point group 23) have been described in detail. The non-centrosymmetric class 43 m. which is not optically active has one non-vanishing piezo-rotatory coefficient, showing that stress induces optical activity in it. A method of retrieving this coefficient has also been described. In most of the other point groups, the difficulty of measuring optical activity in directions other than those of the optic axes severely limits the number of coefficients that can be extracted. The paper also touches upon some interesting methods of obtaining the components of the gyration tensor in non-enantiomorphic optically active crystals.