The application of pulsed slit-jet expansion sources in sub-Doppler degenerate four-wave mixing spectroscopy

Sub-Doppler degenerate four-wave mixing (DFWM) spectroscopy has been performed on carbon disulfide (CS2) molecules entrained in a pulsed slit-jet expansion of modest dimensions (i.e. ≈ 1 cm slit length). Data obtained for the 10V band in the V1B2(1Δu) ← X̃ 1Σg+ (π∗ ← π) absorption system (≈ 323.7 nm) demonstrate significant enhancements in sensitivity and resolution over that obtained through use of a conventional free-jet source based upon a circular nozzle orifice. These observations are quantified and interpreted in terms of the increase in effective sample interaction length that accompanies collapse of the transverse velocity distribution in a slit-jet expansion.