Regensburg 2013 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 27: Nanoparticles and Composite Materials II

CPP 27.3: Talk

Wednesday, March 13, 2013, 15:30–15:45, H39

Fluorescence spectroscopy of individual semiconductor nanocrystals in solution — •Sandra Flessau and Alf Mews — Institute for Physical Chemistry, University of Hamburg

Colloidal II-VI semiconductor nanocrystals are crystalline fragments of the corresponding bulk material with sizes of 1 to 10 nm. In this range, the surface-to-volume ratio is considerably large. For a CdSe nanocrystal of 3 nm in diameter, already one third of its atoms is at the surface. The states of the surface influence charge carriers which are three-dimensionally confined within this volume, and therefore become important in determining many of the nanocrystal properties like fluorescence intensity, fluorescence lifetime and blinking behavior.

Here, we present experiments on the impact of chemical or physical modification of the surface on individual nanocrystals. Therefore, the nanocrystals are immobilized within microfluidic channels which are fabricated by soft lithography. Time-resolved single particle fluorescence spectroscopy is performed to explore the details of photophysical changes of one and the same nanocrystal before and after rinsing the channel with varying solutions, e.g. with different dielectric properties or which contain different molecules that can attach to the nanocrystal surface.