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We present observations of previously unreported excited-state wave packets in the methanol solvated oxazine dye LD690. We have been able to monitor the dephasing of certain excited-state wave packets despite complications caused by the presence of oscillations which originate from the ground state. We have also measured resonant impulsive stimulated Raman scattering (IRSR) from the solute without undue interference from nonresonant solvent ISRS. This allows us to demonstrate that the dominant contribution to the oscillatory features in the transient absorption experiments is from probe absorption/stimulated emission rather than from ISRS.

The temperature behavior of zero-phonon lines and phonon sidebands of bound excitons is carefully studied. In the very-low-temperature range, the internal transition between exciton A and 8 causes a decrease in the luminescence intensity of zero-phonon lines with decreasing temperature. In different temperature ranges, the different activation energies indicate that the thermal quenching of bound excitons consists of three mechanisms: the ionization of the free exciton, the escape of the hole, and the debinding of the whole bound exciton. We also develop a model for the cornponents of phonon sidebands to explain the fact that the thermal quenching of the phonon sidebands does not have the same temperature behavior as the corresponding zero-phonon lines.