THE NU(1)-NU(10) HOT-BAND IN PROPYNE STUDIED IN A BIMOLECULAR SEEDED JET(NU(10))

IR-IR double resonance jet spectroscopy has been used to record the nu (10) + nu(10) - nu(10) hot band in propyne at low rotational temperatu re. Population has been pumped into the nu(10) manifold in propyne thr ough 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 proce dures yield an upper state B constant of 0.285160(4) cm(-1). From the splitting of the K = 1 sub-band, the Coriolis interaction constant A z eta has been determined to be 4.73120(17) cm(-1). The difference in l- type doubling constant q(v) between upper and lower state has been est imated from the tiny A(1)-A(2) splitting of the kl = + 1 sub-band for high J-values.