Coincidence studies with polarisation analysis of the photon emission induced inK-inert gas collisions

Abstract

The linear and circular polarisations of theK(42P→42S) transition detected in delayed coincidence with the inelastically scattered potassium atom are presented forK- He, Ne, Ar, Kr and Xe. For all systems the Stokes vector measurements have been performed as a function of the potassium scattering angle at a beam energy of 103 eV. The coherence properties of the excitation process are studied with the help of the measured degree of polarisation. For He, Ne and Xe the excitation amplitudes (e.g. the parametersλ andχ) are deduced from the measured Stokes vector. For Ar and Kr the collisionally excited state is not a pure state, and it is concluded that both single excitation of theK atom and simultaneous excitation of both collision partners contribute toK(42P) excitation. The results are compared with the predictions of the semiclassical treatment of the excitation process.