IR spectroscopy with FELIX Part 2.—Lowest triplet state of azabenzenes

Abstract

IR spectra of the lowest triplet state T₀ of pyrazine, pyrimidine and pyridine have been recorded by the use of the free-electron laser FELIX. Vibrational transitions have been observed as laser-induced changes in the intensity of the phosphorescence from T₀. Five triplet vibrations have been recognised for pyrimidine and two for pyridine. For pyrazine, all seven fundamental IR-active triplet vibrations in the range 250–2000 cm^-1 have been detected and the vibrational frequencies are found to be considerably lower than the corresponding ones in the ground state.

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