Spontaneous emission of a nanoscopic emitter in a strongly scattering disordered medium P. V. Ruijgrok, 1 ∗ R. W¨ uest, $^{1}$† A. A. Rebane $^{1}$, A. Renn$^{1}$, and V. Sandoghdar 1 ‡ $^{1}$Laboratory of Physical Chemistry and optETH, ETH Z¨ urich, CH-8093 Z¨ urich, Switzerland ∗ Present address: Huygens Laboratory, Leiden University, 2300 RA Leiden, The Netherlands † Present address: ABB Ltd, Corporate Research, CH-5405 Baden-D¨ attwil, Switzerland ‡ vahid.sandoghdar@ethz.ch http://www.nano-optics.ethz.ch Fluorescence lifetimes of nitrogen-vacancy color centers in individual diamond nanocrystals were measured at the interface between a glass substrate and a strongly scattering medium. Comparison of the results with values recorded from the same nanocrystals at the glass-air interface revealed fluctuations of fluorescence lifetimes in the scattering medium. After discussing a range of possible systematic effects, we attribute the observed lengthening of the lifetimes to the reduction of the local density of states. Our approach is very promising for exploring the strong three-dimensional localization of light directly on the microscopic scale. PACS numbers: 1 Abstract arXiv:1001.3882v1 [quant-ph] 21 Jan 2010