Rovibrational and rotational spectroscopy of levels of propyne around 1000cm(-1)

Four vibrational levels in the energy region around 1000 cm(-1) were studie d. These were the upsilon (5) = 1 and upsilon (8) = 1 fundamental levels, b oth components of the upsilon (9) = upsilon (10) = 1 combination level (iot a (9) = iota (10) = +/-1 and iota (9) = -l(10) = +/-1), and both components of the upsilon (10) = 3 overtone level (iota (10) = +/-1 and +/-3). New FT IR spectra with a synchrotron radiation source were recorded in the region of the "superhot" upsilon (10) = 3 <-- 2 bands, which made possible the fir st assignment of levels of the upsilon (10) = 3(+/-1) sublevel. More than 3 30 new rotational transitions in the combination and overtone levels were m easured by millimeter-wave spectroscopy betwen 50 and 360 GHz. The new data were analyzed simultaneously together with the previously assigned rovibra tional data for the fundamental and combination levels and rotational data for the fundamental levels using a global model with all anharmonic, Coriol is, iota -type, and alpha -resonances. Significant improvement of data repr oduction and very good consistency with the Hamiltonian parameters of the l ower vibrational levels upsilon (9) = 1 and upsilon (10) = 1, 2 were achiev ed. A strong dependence of the A(upsilon) constant on the iota (10) quantum number is found for propyne: this is shown to be characteristic of skeleto n C-C equivalent toC or C-C equivalent toN bending modes in H3CCCH, H3CCN. and their fully deuterated species, (C) 2001 Academic Press.