A picosecond 248 nm KrF* laser system producing a focal intensity of greater than 1015 W/cm2 has been used to study VUV fluorescence and harmonic generation in H2, He, Ne,'Ar, Kr, and Xe. The nonlinear media were found to fall into two distinct classes: the lighter materials, H2, He, and Ne, which readily support the generation of harmonic radiation, but do not fluoresce, and the heavier materials, Ar, Kr, and Xe, which produce significant amounts of fluorescence, but in which the generation of harmonic radiation decreases rapidly with the scattering order.
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