Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 15: Poster Session

MM 15.81: Poster

Monday, March 11, 2013, 18:00–20:00, Poster E

Electron irradiation effects on QDs in TEM and SEM — •Thomas Kister, Ute Golla-Schindler, and Ute Kaiser — Group of Electron Microscopy of Materials Science, Central Facility of Electron Microscopy, Albert-Einstein-Allee 11, 89081 Ulm, Germany

Monodisperse CdSe/CdZnS QDs, which are capped with trioctylphosphine oxide (TOPO), have a high fluorescence quantum yield. They are for example supposed to be used in the near future as marker for biological matter in medicine. Up to now the chemical and structural constitution on the atomic level is not well known. Unfortunately, in the initial investigation it was indicated that QDs are losing their fluorescence abilities dramatically by electron irradiation already at low dose rates. Therefore we started systematic studies of radiation damage dependence on dose, dose rate and accelerating voltage. For the experiments the TOPO-capped QDs, which are suspended in hexane, are deposited on carbon and silicon oxide filmed TEM-grids. The fluorescence of the QDs is measured before and after electron irradiation with an optical microscope (Zeiss Axioscope 2 mot plus). A Philips CM20 TEM and a Zeiss NVision 40 SEM are used for the electron irradiation investigations. Through these experiments we hope to get a better understanding of the interaction and irradiation mechanisms taking place during the electron microscopy studies.