Pulsed free jets: Novel nonlinear media for generation of vacuum ultraviolet and extreme ultraviolet radiation

We describe the application of free jets for the frequency tripling of laser radiation. Using a supersonic expansion of Xe we obtain ∼5 × 1011 photons/pulse at 118.2 nm for an input power of 18 MW at 354.7 nm, while for CO we obtain ∼1 × 1012 photons/pulse at 98.5 nm for an input power of 2 MW at 295.6 nm. In the latter case the conversion efficiency is enhanced by a two-photon resonance via the CO A1Π state. A simple model is presented for third harmonic generation in a free jet, and the predictions of this model are tested against experiment. © 1984 American Chemical Society.