To obtain further information on the dynamics, we measured TA spectra in toluene and in THF shown in Figures and, respectively. A common feature of the TA spectra between the two solvents is that a significant spectral change is observed up to 20 ps and no spectral change is observed after 20 ps. Figures and compare the normalized TA spectra at 100 ps and 1000 ps in toluene and in THF, respectively. To clarify this situation, we compared the temporal profiles ranging from -1.0 ps to 30 ps at longer wavelengths (700 nm for toluene solution, 725 nm for THF solution) and at shorter wavelengths (600 nm for toluene solution and 621 nm for THF solution) shown in Figures and, respectively. At the longer wavelengths, both the profiles are quickly increased less than 1 ps followed by a gradual increase over 20 ps. On the other hand, at the shorter wavelengths, both the profiles are quickly increased less than 1 ps followed by a gradual decrease over 20 ps. Considering that q-ax. partially undergoes a structural change into q-eq. as shown in Figure , both the gradual increase and decrease are assigned to the structural change from q-ax. to q-eq. in the excited states. By the least squares fit using exponential functions, the time constants of structural changes are determined to be 8.0 ± 0.75 ps in toluene and 6.6 ± 0.98 ps in THF. These values are consistent with the time constant for the structural change of ~1.8 ps in the hexane solution reported in the literature , considering that the difference in the observed signal between PL and TA.