Abstract

This talk presents spectroscopic evidence for the existence of the four-atomic rare gas halide exciplex Ar₃F.¹ It is identified through its broadband emission from electron beam excited high pressure Ar/F₂ and Ar/NF₃ mixtures at (435 ± 50) nm. The temporal behavior of the Ar₃F emission as well as the Ar₂F/Ar₃F intensity ratio shows that the four-atomic species is produced by three-body collisions from Ar₂F. However, it is easily destroyed by two-body collisions due to its small binding energy of < 0.2 eV, which can be inferred from the binding energy of ${\text{Ar}}_3^{+}$. The assignment of the blue emission continuum is further confirmed by the observation of a similar, previously unassigned emission from liquid Ar/F₂ mixtures.² Abnormalities in the Ar₂F kinetics found in earlier investigations can now be partially explained by the formation of Ar₃F, and partially by electron quenching of ArF and Ar₂F. The existence of four-atomic rare gas halide exciplexes could impact on the absorption behavior of rare gas halide lasers. Recently, doubts have been raised as to whether the main absorber in the KrF lasers is, in fact, Kr₂F, because the absorption cross section of this molecule appears to be too small. The possible formation of four-atomic exciplexes has to be taken into account for the determination of the absorption cross sections of trimers, as well as for the investigation of scalability of rare gas halide lasers.

© 1986 Optical Society of America