1. Institute of Physics, University of Stuttgart, Stuttgart, Germany
2. Structure and Activity of Normal and Pathological Biomolecules, INSERM/UEVE U829, Bat. Maupertuis, rue du père Jarlan 91025 Evry, France
3. Centre des Matériaux, Mines-ParisTech, UMR7633 BP 87, 91003 Evry Cedex, France
4. Johannes Gutenberg-Universität Mainz, Johann-Joachim-Becher-Weg 45, D-55099 Mainz, Germany
5. PicoQuant GmbH, Rudower Chaussee 29, D-12489 Berlin, Germany
6. Texas A&M University, College Station, Texas 77843