A NEW TECHNIQUE IN THE THEORY OF ANGULAR-DISTRIBUTIONS IN ATOMIC PROCESSES - THE ANGULAR-DISTRIBUTION OF PHOTOELECTRONS IN SINGLE AND DOUBLE PHOTOIONIZATION

Special reduction formulae for bipolar harmonics with higher ranks of internal spherical functions are derived, which will be useful in prob lems involving multiple expansions in spherical functions. Together wi th irreducible tensor operator techniques these results provide a new and effective approach, which enables one to extract the geometrical a nd dynamical factors from the cross sections of atomic processes with polarized particles with an accurate account of all the polarization e ffects. The angular distribution of polarized electrons and the circul ar dichroism in photoionization of polarized atoms with an arbitrary a ngular momentum J(0) are presented in an invariant vector form. A spec ific circular dichroism, which is caused by the correlation of electro n and atom orientations, is discussed. The angular distribution of esc aping electrons in double photoionization of unpolarized atom is prese nted in a simple form. A convenient parametrization is proposed for de scribing the dependence of the photoprocess cross sections on the pola rization state of the photon beam.