Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 25: POSTER Electronic Structure and Spectroscopy
CPP 25.10: Poster
Donnerstag, 30. März 2006, 17:00–19:00, P2
Defocused Wide Field Imaging of Single Quantum Dots — •Roman Schuster1, Michael Barth2, Rebecca Wagner3, Achim Gruber3, Thomas Blaudeck3, and Frank Cichos3 — 1Leibniz Institute for Solid State and Materials Research Dresden, 01171 Dresden — 2Nano-Optics group, Institute of Physics, Humboldt University Berlin, Hausvogteiplatz 5-7, 10117 Berlin — 3Photonics and Optical Materials, Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz
We have applied fluorescence wide-field imaging to study the details of the transition moment of single CdSe/ZnS core/shell quantum dots. [1] Introducing a slight defocusing into the imaging creates a well resolved pattern from the light emitted by a single quantum dot. This pattern is a consequence of the diffraction of the light on the aperture of the microscope objective and contains information on the angular anisotropy of the light emitted by the quantum dot. By comparing these images to numerical calculations of the diffraction patterns we find, that the transition moment of CdSe quantum dots is not circular at room temperature. All images can be either fitted with an elliptical transition moment or even a 3-dimensional transition moment. The results suggest that the transition moment at room temperature is more complex than so far suggested and determined by the mixing of different valence band states, which form finally a 3-dimensional transition moment. A combination of different polarization projection methods with defocused imaging are evaluated to unraval the details of the 3-dimensional transition moment.
[1] R. Schuster et al., Chem. Phys. Lett.,2005 , 413, 280.