UV transient absorptions in high pressure argon excited by relativistic electrons

Abstract

Several new laser effects have been obtained by using electron beam pumped mixtures of a rare gas with another gas. Nevertheless, the laser action in those media appears to be very sensitive to the effect of a transient absorption which can be due to the rare gas itself. Also in this work we have made an experimental study of transient absorptions in the near UV (250–450 nm) for a high pressure of argon excited by relativistic electrons. Two different absorptions have been identified in the present work: (1) A ’’long time’’ absorption attributed to Ar2*(3Σu); the experimental value of its cross section has been found to be in satisfactory agreement with the theoretical one; (2) a ’’short time’’ absorption which exhibits a very broad spectral width, the origin of which is discussed.