Spin-effects in the ionisation-with-excitation of krypton atoms by polarised electrons

Abstract

Ionisation-with-excitation has been studied for the krypton excited ionic 5p 4 P 3/2 4 P 5/2 and 4 D 7/2 states which decay by emission of photons of wavelengths 465.9, 473.9 and 435.6 nm, respectively, to the lower ionic 5s 4 P 5/2 state. The integrated Stokes parameters of these photons are measured near threshold with polarised electrons and the coincidence counts between the scattered electrons and the decay photons as a function of the ejected electron energy and scattering angles are measured with unpolarised electrons. The integral polarisation data indicate that the residual ions can be aligned and oriented. The electron exchange process plays a significant role and the spin-orbit interactions are less important than the exchange process near threshold. The coincidence measurements show the interference between ionisation-with-excitation and excitation of doubly-excited states.