Femto-Fourier transform-cavity enhanced absorption spectroscopy in a supersonic expansion

Proofs of principle spectra of C₂H₄, N₂O and C₂H₂, including H¹²C¹³CH in natural abundance, are reported, recorded in the 1.6?µm range in an Ar supersonic expansion using femto-Fourier transform–cavity enhanced absorption spectroscopy. The effective absorption pathlength in the jet-cooled sample is up to 78?m and the optimal S/N is over 2300. The data processing is detailed. Saturation effects are reported for the C₂H₂ bands.