Cavity-enhanced frequency comb spectroscopy in a supersonic jet
Résumé
Reaching low temperatures is of great interest for precision spectroscopy, as it simplifies rovibrationnal spectra of large molecules. Efficient cooling can be achieved via the supersonic expansion of a gas through a nozzle, which can be probed using cavity-enhanced spectroscopy [4]. The comb filtered by the cavity had a frep= 707MHz, and two-burst interferograms were acquired, yielding comb mode resolution [4]. A mixture of 90% Ar and 10% C2H2 was expanded from a reservoir at 16 Torr into a chamber at 0.35 Torr through an aerospike nozzle. The isentropic core of the resulting supersonic jet exhibited a rotational temperature of 140 K and was surrounded by shear layers and residual gas at room temperature.