Sub-doppler infrared absorption spectroscopy of Ar-HF [(10 00) ← (00 00)] in a linear supersonic jet

Abstract

Ultra-sensitive tunable difference frequency IR absorption spectroscopy in a slit supersonic jet has been used to observe sub-Doppler spectra of Ar-HF in the (10 00) HF stretch and (11 10) HF stretch plus van der Waals bend modes. Linewidths yield a lower limit of 3 × 10 −9 s for the predissociation lifetime in the vibrationally metastable upper state. The sensitivity of these direct absorption methods (≲ 2 × 10 9 molecules/cm 3 per quantum state), in conjunction with the wide tunability of the difference frequency laser (2.2–4.2 μm) permit high-resolution studies of a large class of van der Waals complexes.