DYNAMICAL AND GEOMETRICAL PROPERTIES OF THE CIRCULAR-DICHROISM IN ONE-PHOTON DOUBLE-IONIZATION

The helicity dependence of the two-electron photoemission from isotrop ic targets is analysed. As prototype reactions, we consider the double ionization of H-(S-1(e)), He(S-1(e)), Li+(S-1(e)), Be2+(S-1(e)) and B 3+(S-1(e)) upon the absorption of a circularly polarized photon. Assum ing the Coulomb field of the nucleus to be dominant over other involve d interactions, we derive analytical expressions for the cross section s and their dependence on the photon helicity, i.e. for the circular d ichroism in these cross sections. This analysis indicates that the cro ss sections and the circular dichroism are influenced in a markedly di fferent manner by the interelectronic correlation. With increasing str ength of the Coulomb nuclear field the cross section rapidly diminishe s whilst the dichroism remains finite and its sign varies considerably with the nuclear charge. It is analytically concluded that the absenc e of the dichroism at certain 'non-geometrical' points as well as at c ertain intermediate excess energies is a direct manifestation of the i nterelectronic correlation. At threshold and in the high-energy limit negligible dichroism is anticipated.