Electronic absorption (π*←n) spectrum of methoxypyrazine

The π•→n electronic absorption system of methoxypyrazine, corresponding to the 1 B 3u ← i A g transition of pyrazine has been recorded in vapour phase and in solution of cyclohexane. Vibrational analysis of the electronic spectra has shown the existence of a vibronic interaction between two electronic states of methoxypyrazine, through an out-of-plane bending mode. The Raman and infrared spectra of this molecule have also been recorded in the pure liquid phase and analysed