Excitonic luminescence in the drift of excess electrons through liquid and solid rare gases

Abstract

It is shown that the excitation of electronic states is the main channel of energy loss of excess electrons drifting in moderate (⩾103 V/cm) electric fields through condensed heavy rare gases (Rg). These losses, together with scattering on resonances of metastable negative ions (Rg*)−, determine the dependence of the average energy of the electrons and their drift velocity vd on the electric field E both in condensed Rg and in dense gases. In particular, explanations are given for the constancy of vd at large E and for the transformation of the electroluminescence spectrum upon changes in the density of heavy particles and their temperature. Thus it is predicted that localized excitons can be efficiently excited in the bulk of crystalline and liquid Xe, Kr, and Ar, with a yield of around 102 excitons (and UV photons) per electron.