Recent Developments of Resonant Auger Transitions: Predictions and Propensity Rules for the Dynamic Spin Polarisation

Abstract

The angular distribution and spin polarisation of the resonantly photoexcited Xe^¤(4d^–1_5/2 6p_3/2 ) N₅O_2,3O_2,3 Auger spectrum is investigated. The two-step model has been used which allows us to independently determine the dynamic parameters of the primary excitation and the Auger emission process. Assuming either a fully circularly or linearly polarised photon beam the dynamic parameters determining the primary photoexcitation become constant numbers independent of the matrix elements. Applying a relativistic distorted wave approximation the relevant numbers describing the Auger decay dynamics, i.e. relative intensities, angular distribution and spin polarisation parameters have been calculated, and are compared with experimental and other theoretical data. With this, predictions for the spin polarisation vector are possible. A large degree of dynamic spin polarisation has been found for all Auger transitions to a final state with J_f = ½ . This is in contrast to earlier calculations for diagram Auger transitions. Recently, we have given an explanation for this deriving propensity rules for resonant Auger transitions. The propensity rules allow for predictions for which Auger line a large dynamic spin polarisation can be expected. The predictions are in accord with our multiconfigurational Dirac–Fock calculations for the resonant Xe N₅O_2,3O_2,3 and Ar L₃M_2,3M_2,3 Auger multiplets. It is demonstrated that the effect of a large spin polarisation is caused by a large shift of the scattering phase of the emitted &epsis;s_1/2 partial waves, whereas a small spin polarisation is due to a cancellation between the Coulomb and scattering phases of the partial waves.