The angular distribution of collision products is expressed as a sum of incoherent contributions corresponding to different magnitudes of the angular momentum ${\overrightarrow{\mathrm{j}}}_t$ transferred to an unpolarized target. For targets with a characteristic internal reference frame (e.g., molecules) the coefficients of this sum are interpreted as generalized $2^{j}t$-pole polarizabilities of the target in its internal reference frame, analogous to the scalar and quadrupole polarizabilities that determine the Raman effect. The theory is developed in the context of photoionization, but is applicable to more general collision processes as well. It is illustrated by use and extension of diagrammatic techniques.

• Received 10 December 1971

DOI:https://doi.org/10.1103/PhysRevA.6.185