Fluorescence Enhancement of CdSe Q-Dots with Intense Femtosecond Laser Irradiation

Effects of intense femtosecond (fs) laser irradiation on the optical properties of cadmium selenide (CdSe) nanocrystals are studied. We present the changes in emission and absorption of laser (800 nm, 110 fs, Ti–Sapphire) irradiated CdSe nanocrystals dispersed in dimethylformamide (DMF). It is observed that the absorbance of CdSe nanocrystals capped with trioctylphosphine (TOP) increases with the number of laser pulses. The trap state luminescence intensity of these crystals degrades, whereas the band edge luminescence intensity shows an increase as a function of the fs laser irradiation. We also report strong two photon absorption and reduction in the trap state luminescence intensity after irradiation with the laser pulses.