Time-resolved stimulated emission spectroscopy in the ultrashort domain through pump–probe experiments

The photoemission properties of fluorescent chromophores have a widespread application in many fields ranging from chemical-physics and biology to organic light emitting devices. These systems usually display high fluorescence conversion efficiency, which makes them suitable for transient/gain experiments also in liquid solutions, thin films and eventually in protein environments. Pump and probe methods have been widely employed for wavelength-resolved spectroscopy in the subpicosecond time scale. In our group, we have recently assembled a new experimental setup for pump and probe spectroscopy: preliminary tests on the Rhodamine B dye in ethanol have been performed in order to optimize the setup. The dynamic response of photoinduced changes of the chromophore dispersed into a suitable solvent has been studied with a subpicosecond time resolution. The optically prepared initial state of the Rhodamine B in ethanol solution appears to evolve on a timescale of few picoseconds into a successive state, which could be attributed to an intramolecular charge transfer state.