The absolute rates of radiative and of nonradiative decay from three vibronic levels in isolated 1B2u benzene molecules

Lifetimes in Excited States

“…There now seems to be some question as to whether lifetimes determined in electron impact excitation can be compared to lifetimes determined by photoexcitation (300,301). More recently measurements in the 0.1-0.4 torr region have been possible but only six vibronic levels have been reported (94,300,302), and three of these have been correlated with quantum yield data (95) to extra�t the individual rate constants, as discussed above. Hence our understanding of benzene, not from a spectroscopic but from a rate constant point of view, is as yet very meager.…”

“…Hence our understanding of benzene, not from a spectroscopic but from a rate constant point of view, is as yet very meager. The results are interpreted to show that the Franck-Condon factors are decreasing logarithmically with the energy gap (20,95). The resolution of the individual bands was possible because the absorption lines are sufficiently separated to illuminate with the 2-20 A bandwidths required for go o d detectability.…”

“…Gelbart et al assume further that the C-H stretching mode acts as the main accepting mode and find an increase of the rate constant by 1.2, 1.4, and 1.6 as one excites by 1, 2, and 3 quanta, respectively. Experimental values by Ware et al (95) have been analyzed by Siebrand (96), who uses the density of states model (D) and discusses the Franck-Condon factors of specific normal modes. He makes a definitive prediction in the case where a nontotally symmetric mode is excited.…”

Doppler-Free Two-Photon Excitation Spectroscopy and the Zeeman Effects. Perturbations in the and Bands of the S1← S0Transition of C6D6

“…Benzene is a prototype aromatic molecule, and the dynamics in the excited states has been studied extensively. − Electronic relaxation from the S 1 state can occur via three pathways: radiative transition to the S 0 state, nonradiative transition to isoenergetic levels of vibrationally highly excited levels of the S 0 state (internal conversion: IC), and the one of a triplet state (intersystem crossing: ISC). The fluorescence quantum yield of the S 1 1 B 2u state of an isolated benzene was observed to be small, and the electronic nonradiative decay was attributed to ISC. − …”

“…The fluorescence quantum yield of the S 1 1 B 2u state of an isolated benzene was observed to be small, and the electronic nonradiative decay was attributed to ISC. [5][6][7][8] Extremely high-resolution can be achieved by Doppler-free two-photon excitation (DFTPE) spectroscopy, and this technique was successfully applied to benzene more than 20 years ago. [9][10][11] DFTPE spectra of the 1 0 1 14 0 1 and 14 0 1 bands of C 6 D 6 were measured by Sieber et al 11 Only a part of the J ) K lines were assigned in the 1 0 1 14 0 1 band, and the rotational structure was reported to be impossible to analyze.…”