Generation of tunable, fcintosecond-tiinc-scale, vuv pulses by four-wave difference-frequency mixing in xenon

A practical method for generating femtosecond-time-scale VUV pulses in the spectral range 150-200 nm is discussed. The method is based upon four-wave difference-frequency mixing in Xe (w3 = 2w1-w2). One can utilize a two-photon resonance in Xe to increase the VUV output energy by almost two orders of magnitude by choosing the beam at a>\ to be a KrF-excimer-amplificd ultrashort pulse. This resonantly-enhanced mixing process is utilized to generate ~4-//J, fcmtosccond-time-scalc, pulses at ~156 nm, suitable for use as seed pulses to test the ultrafast amplification characteristics of/^-discharges.