Abstract
The application of liquid-crystal glasses in triplet ESR spectroscopy is described. Anisotropic glasses have been prepared from electric field oriented nematic mixtures of cholesteryl chloride and cholesteryl laurate (1.85:1 by weight) by rapid cooling. The partial alignment of the molecules affects the triplet ESR lineshape in a characteristic way. By analyzing these changes in the ESR lineshape the elements of the zero-field-splitting (ZFS) tensor may be assigned to the molecular axes in a very simple way. For the quantitative analysis of the ESR lineshape an exponential orientation distribution function of the solute is assumed. The average orientations of the molecular axes (i.e., the elements of the Saupe order matrix) are expressed in terms of orientational constants c x i . For the symmetrical molecules studied in this work the coefficients c x i are both proportional to the principal polarizabilities and to the Van der Waals dimensions in the direction of the symmetry axes x i .
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