Vibrational relaxation in pyridine upon supersonic expansion

The rotational spectra of five vibrational states of pyridine have been ass igned and measured by millimeter wave absorption spectroscopy in a superson ic expansion. The intensities of the lines of the vibrational satellites wi th respect to the ground state after the supersonic expansion depend on the kind of carrier gas, backing pressure, pyridine concentration, and symmetr y of the rotational and vibrational states. Several rotational transitions of the vibrational satellites have also been measured in a conventional cel l to complete the spectral assignment. (C) 2000 American Institute of Physi cs. [S0021-9606(00)50543-1].