Simple formulas for rotation averages of spectroscopic intensities

Journal article, 1979

We give a self-contained exposition of the “ensemble method”, a rule for calculating rotation averages of spectroscopic absorption intensities. The rule is mathematically exact and conceptually simple and applies to rotation averages for several axes of rotation occurring in helical and superhelical symmetry. A measure of dichroism, DI, is introduced which has a simple multiplicative property relative to axes of rotation. There are several applications to linear dichroism spectroscopy.