Analysis of Rotational Transitions in Excited Vibrational States of Propionitrile (C2H5CN).

We have observed rotational transitions of propionitrile (C2H5CN) in the 8-200 GHz region and assigned 208 transitions with J </= 16 and Ka </= 2 in the first excited state of torsional vibration, 244 transitions with J </= 16 and Ka </= 2 in the first excited state of CCN in-plane bending vibration, and 374 transitions with J </= 16 and Ka </= 4 in the first excited state of CCN out-of-plane bending vibration. We simultaneously analyzed these transitions in the three excited vibrational states, combining with the previously reported transitions in the ground vibrational state, on the basis of a Hamiltonian including CCN-bending vibration-torsion-rotation interactions. A total of 1560 transitions were fitted with 0.95-MHz 1varsigma standard deviation, and molecular constants were determined. Copyright 1999 Academic Press.