GENERAL FORMULAS FOR DESCRIBING ABSORPTION OF POLARIZED PHOTONS BY ORIENTED NUCLEI

The cross section for the absorption of polarized photons by oriented nuclei is given in terms of the nuclear orientation parameters and the photon polarization parameters for linear and circular polarization. All quantities are given in terms of the nuclear polarizabilities, which contain the electric and magnetic transition matrix elements. The polarizabilities of higher than zero rank contribute to the absorption cross section only if the nucleus is oriented. Without photon polarization, only the even-rank polarizabilities affect the absorption cross section. Photon polarization effects show up only with oriented nuclei. In that case the polarizabilities of odd rank are connected with circular photon polarization, while those of even rank are connected with linear photon polarization. The latter is not true if time-reversal invariance is violated. Finally, the contributions of the various multipole transitions to the polarizability of given rank cannot be separated experimentally. © 1968 The American Physical Society.