Vibronic emission spectrum of p-xylyl radical

We have obtained high-resolution Fourier transform emission spectra of the (A) over tilde <-> (X) over tilde transition of the jet-cooled p-xylyl radi cal in the 450-nm spectral region. The band contours of several vibronic ba nds are examined. By using the rotational constants obtained from previous high-resolution LIF spectra and information about the torsional constants f rom dispersed fluorescence experiments, both a-type and b-type band contour s are simulated. Based on symmetry arguments and the results of the simulat ion, we have reassigned the 6a and 6b vibrational mode frequencies of the g round electronic state of the p-xylyl radical. (C) 1999 Academic Press.