Internal spin-orbit coupling and electronexchange in the excitation ofnp5(n + 1)pstates of neon, krypton and xenon atoms bypolarized electrons

Abstract

Excitation ofnp5(n + 1)pstates by polarized electronshas been studied for target atoms of neon,krypton and xenon. Theintegrated state multipoles have been determinedfrom the measurement of the integrated Stokesparameters of the corresponding decay photonsfrom the excited states ofnp5(n + 1)p[5/2]3,np5(n + 1)p'[3/2]2and np5(n + 1)p'[3/2]1(n = 3, 5 and 6 for Ne, Kr and Xe, respectively)within 2.5 eV of threshold. It is found that thecombined effects of electron exchange with theinternal spin-orbit interaction play a significantrole in the excitations of the aboveJ = 2 and 1 states. Negative angular momentumtransfer is observed in theexcitation of these J = 2 and 1 states of Krand Xe atoms, and it isattributed to internal spin-orbit interactions.Pure electron exchange isthe mechanism for the excitation of all theJ = 3 LS-coupled states, sincethey show no experimental evidence ofspin-orbit interaction. Althoughthe general behaviour of the deduced statemultipoles is in agreement withpredictions from semi-relativisticR-matrix (close-coupling)calculations, there remain differences of detailthat are most notable for theT(J)20 multipole of theJ = 1 states of all of these atoms.