Polarization induced control of multiple fluorescence from a molecule

We show novel dual fluorescent behavior of a popular indocyanine dye molecule, IR125, in dimethyl-sulfoxide solvent when excited at 527 nm instead of the conventional near-infrared excitation. We argue that the dual fluorescence at 571 nm and at 851 nm are from two excited electronic states of IR125. Intensity of dual fluorescence changes as a function of incident laser polarization. All fluorescence intensities are higher for circular polarization as compared to linear or elliptical polarizations. Such enhanced fluorescence for circular polarization component of incident laser at different laser powers indicates involvement of higher excited states in the fluorescence of IR125.