Surface-tuned three-photon absorption of CdSe nanocrystals in near-infrared.

We studied the tunable three-photon absorption (3PA) response of colloidal CdSe nanocrystals in near-infrared by surface states which were successfully controlled with a purification process. The 3PA cross section at room temperature was decreased by more than two orders of magnitude when the density of surface traps increases and works through the photoinduced and intrinsic dipole moments of excitons, indicating that the surface-tuned three-photon absorption of CdSe was of significance in potential applications. [ABSTRACT FROM AUTHOR]