title: Photoactivation of CdSe/ZnS quantum dots embedded in silica colloids.
abstract: A study of the influence of the local environment on the light-induced luminescence enhancement of CdSe/ZnS quantum dots (QD) embedded in silica colloids that are dispersed in various solvents is presented. The photoluminescence of the embedded QD is enhanced up to a factor of ten upon photoactivation by ultraviolet or visible light. This enhancement is strongly dependent on the local environment. The thickness-dependent permeability of the silica shell covering the QD controls the influence of the solvent on the QD. If foreign ions are present the activation state is stabilized after termination of the activation, whereas in their absence the process is partially reversible. A new qualitative model for the photoactivation of QD in various environments is developed. It comprises light-induced passivation and subsequent oxidation processes. The embedded QD also retain their fluorescence quantum yield inside living cells. Moreover, they can be activated for many hours in living cells by laser radiation in the visible regime.
authors: Lehrstuhl für Physikalische Chemie I Universität Würzburg Am Hubland, Germany.
authors: Sofia
authors: S
authors: Dembski
authors: Christina
authors: C
authors: Graf
authors: Tim
authors: T
authors: Krüger
authors: Uwe
authors: U
authors: Gbureck
authors: Andrea
authors: A
authors: Ewald
authors: Anne
authors: A
authors: Bock
authors: Eckart
authors: E
authors: Rühl
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D003102:Colloids; D046529:Microscopy, Electron, Transmission; D010777:Photochemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D003102:Colloids; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; D012822:Silicon Dioxide; C058667:cadmium selenide; C031238:zinc sulfide