THE ROLE OF HYPERFINE INTERACTION IN THE DYNAMICS OF S1(1B3U) PYRAZINE

Eigenstates of the rotational states N = 0 and N = 1 of the S1 (B-1(3u )) vibrational ground state of pyrazine interacting with background tr iplet states have been investigated by quantum beat spectroscopy. Mixi ng of triplet states with different total angular momenta J, excluding nuclear spin, has been established by analysis of sub-natural linewid th quantum beat spectra. Anisotropic quantum beats provide an estimate of the eigenstate hyperfine splittings. Consequences of these observa tions on the interpretation of previously recorded high-resolution spe ctra are discussed.