1. Contribution from the Unité 696, INSERM, Palaiseau France, Laboratory for Optics and Biosciences, UMR CNRS 7645, Ecole Polytechnique, Palaiseau, France, Photonique Moléculaire, UMR CNRS 6510, Université de Rennes I, France, and Division of Hematology, Internal Medicine, University of Texas Houston Medical School, Houston, Texas