We have studied in the femtosecond regime the transient dynamics of dichroism (anisotropic absorption), birefringence, and frequency shift induced by an intense femtosecond pump beam in the dye malachite green in solution. Vibrational quantum beats were observed superimposed on the saturated absorption and dispersion signals and quantitatively explained in terms of impulsivestimulated Raman scattering close to an electronic resonance. The selectivity for observation of the vibrations in the two electronic states is described for the different experimental schemes. We discuss the access to vibrational and electronic dynamics in both ground and excited electronic states and compare the possibilities to those of previous techniques.

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Dual frequency pump–probe induced photoabsorption recovery is studied in two triphenylmethane dyes, malachite green and crystal violet, using femtosecond laser pulses. Comparison of the decays observed for different polarization conditions allows us to analyze the symmetry of electronic states. We observe that the simplest C2 or D3 symmetries cannot account for all our observations. In addition to the previously reported electronic relaxation decays, we observe two additional subpicosecond relaxation components. A first rising component is attributed to the conformational relaxation of torsional modes and a faster decay can be interpreted as originating from solvent limited vibrational relaxation. We attribute the solvent dependence of these relaxations to the nonrigid nature of the triphenylmethanes.