We present an investigation of the Xe$_{ 2}$ excimer emission spectrum observed in the near infrared range about 7800 cm$^{ -1}$ in pure Xe gas and in an Ar (90%) --Xe (10%) mixture and obtained by exciting the gas with energetic electrons. The Franck--Condon simulation of the spectrum shape suggests that emission stems from a bound--free molecular transition never studied before. The states involved are assigned as the bound $(3)0_{ u}^{ +} $ state with $6p [1/2]_{ 0}$ atomic limit and the dissociative $(1)0_{ g}^{ +}$ state with $6s [3/2]_{ 1}$ limit. Comparison with the spectrum simulated by using theoretical potentials shows that the dissociative one does not reproduce correctly the spectrum features.
Categories: physics.atom-ph