The n-π transitions of the pyrazine molecule: II. Polarized spectrum in benzene crystal, and anharmonicity in the upper singlet state potential function☆

摘要: Abstract The polarized absorption spectra of pyrazine ( h 4 and d ) in single benzene crystals have been measured at high resolution 2 K. Vibrational assignments the 1 Ag → B 3u (nπ * transition confirmed considerably extended. quartic potential component hydrogen bending mode :Oa has found to originate primarily from vibronic coupling with nearby 2u (ππ ). between in-plane 6a out-of-plane 10a modes is described theoretically, leads further spectral assignments. Other 5 are identified shown combination defects 6a. A for ring could not be explained by coupling.