Dielectric screening--, multiple scattering--, and quantum indistinguishability effects in the IR emission spectrum of Xe₂ excimers in dense Xe gas

We report new measurements of the infrared emission spectrum of Xe$_{2}$ excimers produced by electron impact in dense gas at room temperature. These measurements extend the density range previously explored by a factor of two. We have now reached a pressure $P\approx 3.3 $MPa, corresponding to a gas density $N\approx 8\cdot 10^{26} $m$^{-3}$ in both pure Xe gas and in a Ar--Xe mixture. The analysis of the changes of the spectrum induced by the interaction with the gaseous environment shows how cooperative-- and many-body effects develop with increasing density. We %will also show that quantum effects related to the indistinguishability of identical particles are observed even at such high temperature.