The Lowest Triplet State of 2-Methylpyrazine

Abstract The infrared and Raman spectra of 2-methylpyrazine were studied. An assignment was given for all fundamental vibrations based on the polarization behavior of the spectral bands and on the normal coordinate analysis. The magnetic effect on the phosphorescence lifetime and the time-resolved and polarized phosphorescence spectra of this molecule were investigated at 1.4 K. From the analysis of the phosphorescence, (1) the short lifetime phosphorescence was assigned to the emission arising from the most emissive y″ sublevel, as in the case of pyrazine, (2) the long lifetime phosphorescence was assigned to the emissions arising from the x and z″ sublevels, whose lifetimes were roughly equal to each other and (3) the 0-0 and totally symmetric vibronic bands, and the out-of-plane vibronic bands observed in the long lifetime phosphorescence, were ascribed to the z″ and x sublevel emissions, respectively.