Interpretation of Optical Spectra of Partially Aligned Samples

Spectroscopic studies with linearly or circularly polarized light of partially aligned molecular samples can provide two kinds of important information. One type of information is the molecular · alignment; the complete molecular orientation distribution function can not be found, but its essential properties can be determined, and these frequently enable a detailed interpretation of the spectrum. This leads to the other kind of information, which has to do with the anisotropic molecular optical properties : transition moments, MCD B-terms, Raman polarizability tensors, etc. A survey of the field is given together with a short description of the mathematical treatment of molecular orientation and optical properties. The different spectroscopic methods are illustrated by a number of examples based on absorption, magnetic circular dichroism, and photoluminescence.