Optical dephasing in solution: A line shape and resonance light scattering study of azulene in isopentane and cyclohexane

Abstract

Results of a line shape and resonance light scattering study of the S 1←S 0 and S 2←S 0 electronic transitions of azulene in isopentane and cyclohexane are reported. The results are analyzed using two different non‐Markovian master equations that make different assumptions about the statistical properties of the bath. For both these origin transitions we find that the solution dynamics fall in the so‐called intermediate modulation regime. If exponential decay is assumed for the bath correlation function we obtain a correlation time of the bath of 25 fs for the S 1←S 0 transition and of 13 fs for the S 2←S 0 transition at room temperature. From the frequency dependence of the ratio of fluorescence to Raman yields of the S 1←S 0 transition we calculate an excited state lifetime of 1.4±0.2 ps using the parameters of the bath derived from the line shape analysis, and irrespective of which master equation is used.