The millimetre-wave rotational spectrum of phenylacetylene

The room-temperature rotational spectrum of phenylacetylene (C(6)H(5)C CH), was studied at frequencies up to 340 GHz. Extensive new measurements, covering rotational transitions with quantum number values up to J = 140 and K(a) = 59, allowed determination of precise spectroscopic constants for the ground state and for the lowest two excited vibrational states, v(24) = 1 and v(36) = 1. The two excited states belong to the lowest B(1) and B(2) symmetry normal modes and their rotational transitions are very strongly perturbed by a-axis Coriolis resonance. A successful fit of the resonance is reported, resulting in zeta(a)(24,36) = 0.8403(3) and Delta E = E(36) = E(24) = 15.38994(2)cm(-1), in good agreement with results of ab initio computations. (C) 2010 Elsevier Inc. All rights reserved.