Vibrational energy relaxations of S 1 perylene and S 1 12-(3-perylenyl)dodecanoic acid (PD) in 2-methyltetrahydrofuran at room temperature were investigated by using a Franck-Condon analysis of femtosecond time-resolved fluorescence spectra. Vibrational energy relaxation from |2〉, V′ ) 2 level of ν 7 mode, occurs not only via successive route, |2〉 f |1〉 followed by |1〉 f |0〉, but also via direct route, |2〉 f |0〉. The vibrational energy relaxation times were obtained as 2.7 ps for |2〉 f |1〉, 1.8 ps for |1〉 f |0〉, and 700 fs for |2〉 f |0〉 in perylene and 1.9 ps for |2〉 f |1〉, 1.2 ps for |1〉 f |0〉, and 500 fs for |2〉 f |0〉 in PD. An average-matrix-element treatment proposed by Fourmann et al. (Chem. Phys. 1985, 92, 25) was employed to account for these relaxation times in the Fermi's golden rule. Two parameters of the average-matrix element were estimated to be V 0 ) 0.59 cm -1 and 0.46 < R < 0.55 in our analysis, which were in reasonable agreement with Fourmann's analysis, V 0 ) 0.65 cm -1 and R ) 0.3, for fluorescence spectra of perylene in supersonic jet. To discuss the energy flow in the ν 7 mode, transient vibrational temperatures were also calculated at each time. "Intramode" thermal equilibriums in the ν 7 mode both for perylene and for PD are not established while the vibrational temperature is higher than room temperature.

We investigated vibrational energy relaxations of S 1 perylene at an excess energy of ca. 2800 cm -1 in several ketone solvents by femtosecond time-resolved fluorescence measurements.Temporal evolution of fluorescence emissions occurs on the following distinct timescales: 70 ~ 330 fs, 0.6 ~ 1.1 ps and 1.8 ~ 4.9 ps. The latter two was assigned to the intramolecular vibrational redistribution (IVR), and to the solvent-assisted IVR (SA-IVR), respectively. In SA-IVR, intramolecular vibrational couplings are affected by elastic or quasi-elastic interactions between solute and solvents. Solvent dependence of the SA-IVR rates can be explained qualitatively by the tier V-V coupling mechanism.

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We propose an implementation scheme for the continuous-time quantum walk using a diatomic molecule and an optical frequency comb. We show an analogy between the quantum walk and the cascade rotational transitions induced by the optical frequency comb whose frequency peaks are tuned to the pure rotational transitions in the molecule. The strategy to compensate for the centrifugal distortion of the real molecule is also demonstrated.

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