Rovibrationally resolved, Fourier-transform near infrared spectroscopy of the ν1 and ν2 vibrations of the HCl dimer in a supersonic jet

We have recorded the high-resolution (0.007 cm−1) Fourier-transform near infrared absorption spectrum of the symmetric 35Cl–35Cl, and the mixed 35Cl–37Cl isotopomers of the hydrogen chloride dimer in a supersonic jet. The spectrum was recorded under a low effective rotational temperature (≊20 K). Rovibrational analysis of the observed spectra has been performed for the K″a=0 subbands of the ν+1 and ν−1 perpendicular-type bands centered at 2890 and 2879 cm−1, respectively. The K″a=0 and 1 parallel-type subbands of the ν−2 at 2839 cm−1 and ν+2 at 2857 cm−1 have also been analyzed. Furthermore, we have observed and investigated the (H 35Cl)2ν+1, K″a=1, ΔK=−1 rovibrational transition centered near 2869 cm−1. The results are compared with spectra previously recorded using difference frequency tunable laser spectrometers both in a supersonic slit jet and in an equilibrium gas phase mixture to demonstrate the advantages and limitations of the FTIR technique.