Particle transport in neutral xenon: 2D modelling approach for the contribution of recombination processes to VUV emissions

Abstract

This paper constitutes a first step in studying transport phenomena, consecutive to a very brief two-photon excitation of the Xe(3P2) metastable state in neutral xenon, followed by absorption of a further photon leading to ionization, in two-photon absorption laser-induced fluorescence (TALIF) experiments. Here, the laser beam simply defines the column volume in which electrons and atomic ions are initially confined. Performing a numerical approach, we only consider the reactions occurring once electrons and atomic ions are produced by the incident laser pulse. All metastable atoms initially present are discarded, thus allowing evaluation of the contribution of only recombination processes to the vacuum ultraviolet (VUV) emissions. In addition to kinetics of collisional and radiative processes, we also account for diffusion and possible drift phenomena (in the presence of a Laplacian electric field). We provide spatial distributions of the number densities of the various species as well as temporal profiles of both their total number and the different VUV emissions. The influence of the external electric field and xenon pressure is discussed as well.