K-dependence and temperature dependence of N2-, H2-, and He-broadening coefficients for the J=12-11 transition of acetonitrile CH3C14N located near 220.7 GHz

Extensive experiments on the K = 3 component of the J = 12-11 rotational transition of acetonitrile (CH3CN)-N-14, located near 220.7 GHz, were performed at different temperatures in the range 235-350 K. They allow determining the N2-, H2-, and He-broadening coefficients, as well as their temperature dependences. More specific measurements on all the K-components of the involved transition perturbed by N-2 at 303 K allow to point out a clear decreasing of the broadening coefficient with increasing K. Narrowing effects are clearly observed, and experimental lines were analysed both with Voigt and speed dependent Voigt profiles; but no exhaustive lineshape study was carried out. All the experimental parameters are compared with results derived from a semiclassical calculation of collisional interactions, including electrostatic, induction, and dispersion energy contributions. (c) 2006 Elsevier Inc. All rights reserved.