Prediction of pure electric-dipole two-photon absorption circular dichroism in lanthanide compounds

Standard theories of chiral linear and nonlinear optical effects, such as c ircular intensity differentials and optical activity, require interference between electric-dipole and magnetic-dipole (or higher-order) contributions to the transition moments. Recent experimental and theoretical work on sec ond-harmonic generation processes has shown that in the resonant case, pure electric-dipole contributions to such chiral effects are possible. In this paper, we consider the implications of pure electric-dipole contributions to circular dichroism in two-photon absorption transitions within the 4f(N) configuration of lanthanide ions. We show that in some lanthanide compound s, when several intermediate states are near to resonance, the pure electri c-dipole mechanism can give larger contributions than the standard electric -dipole magnetic-dipole mechanism. (C) 2000 Published by Elsevier Science B .V. All rights reserved.