Electronic and vibrational structures in the S0and S1states of coronene.
We observed the fluorescence excitation spectra and dispersed fluorescence spectra of jet-cooled coronene-h12and coronene-d12. We analyzed the vibronic structures, assuming a planar and sixfold symmetric molecular structure (D6h). The S1state was identified to be B2u1. The S1B2u1←S0A1g1 transition is symmetry forbidden, so the 000band is missing in the fluorescence excitation spectrum. We found a number of vibronic bands that were assigned to the e2gfundamental bands and their combination bands with totally symmetric a1gvibrations. This spectral feature is similar to that of benzene although several strong e2gbands are seen in coronene. The band shape (rotational envelope) was significantly different in each e2gmode. It was shown that degenerate rotational levels were shifted and split by the Coriolis interaction. We calculated the Coriolis parameter using the molecular structure in the S1state and the normal coordinate of each e2gvibrational mode, which were obtained by theoretical calculations. The calculated band shapes well reproduced the observed ones, suggesting that the isolated coronene molecule has D6hsymmetry.
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Sachi
S
Kunishige
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Ayumi
A
Kanaoka
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Toshiharu
T
Katori
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Megumi
M
Kawabata
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Masaaki
M
Baba
Institute for Molecular Science, Okazaki 444-8585, Japan.
Takaya
T
Yamanaka
Institute for Molecular Science, Okazaki 444-8585, Japan.
Shuhei
S
Higashibayashi
Institute for Molecular Science, Okazaki 444-8585, Japan.
Hidehiro
H
Sakurai