HIGH RESOLUTION ABSORPTION SPECTRUM OF THE MOLECULAR EIGENSTATES OF PYRAZINE

$^{1}$ J. Kommandeur, W.A. Majewski, W.L. Meerts and D.W. Pratt, Ann, Rev. Chem, Phys, 38 (1987) 433Author Institution: Fysisch LaboratoriumThe pyrazine molecules serves as a prototype of an intermediate case molecule in the theory of intramolecular radiationless transitions. The main attention is focused on the fluorescence decay of the first excited singlet $(^{1}B_{3u})$ electronic state. For a recent review see [1] and the references therein. The high resolution absorption spectrum of the P, Q and R. branches of the 0-0 electronic transition of pyrazine was recorded with a bolometer in a supersonic molecular beam and a single mode, frequency doubled ring dye laser. A residual Doppler linewidth of 50 MHz was achieved. Simultaneously with the absorption spectrum the laser induced fluorescence spectrum was observed A comparison is made between excitation and absorption inensities of the molecular eigenstate spectra. It is concluded that substantial differences exist between both spectra