Two-photon absorption of Crystal Violet in solutions: Analysis of the solvent effect and aggregation process based on linear and nonlinear absorption spectra

摘要

We report on the aggregation and solvent effects on one-photon absorption (1PA) and two-photon absorption (2PA) spectra of Crystal Violet (CV) chromophore, which is a model octupolar molecule. In the case of the 1PA spectra we have measured the aggregation thresholds for three highly polar solvents (N,N-dimethylformamide, dimethyl sulfoxide and propylene carbonate) and for water solvent as a reference. The 2PA spectra have been measured above the aggregation threshold for all selected solvents, however, the measurements at concentrations below the aggregation threshold were unsuccessful. In all cases the observed solvent effect is noticeable. On the other hand, this effect is not always consistent with the solvent polarity scale. The obtained results indicate that CV in the selected solvents aggregates in the form of sandwich-type dimers. (C) 2016 Elsevier B.V. All rights reserved.