The ν1 + ν10 − ν10 hot band in propyne studied in a bimolecular seeded jet

IR-IR double resonance jet spectroscopy has been used to record the ν1 + ν10 − ν10 hot band in propyne at low rotational temperature. Population has been pumped into the ν10 manifold in propyne through collisional energy transfer from CO2-laser excited SF6 molecules. The R- and Q-branches of the K = 0 sub-band and the P- and R-branches of the K = 1 sub-band have been assigned. Least-squares fitting procedures yield an upper state B constant of 0.285160(4) cm−. From the splitting of the K = 1 sub-band, the Coriolis interaction constant Aζ has been determined to be 4.73120(17) cm−1. The difference in l-type doubling constant qv between upper and lower state has been estimated from the tiny A1 − A2 splitting of the kl = + 1 sub-band for high J-values.