Quantifying the number of color centers in single fluorescent nanodiamonds by photon correlation spectroscopy and Monte Carlo simulation.

The number of negatively charged nitrogen-vacancy centers (N-V)- in fluorescent nanodiamond (FND) has been determined by photon correlation spectroscopy and Monte Carlo simulations at the single particle level. By taking account of the random dipole orientation of the multiple (N-V)- fluorophores and simulating the probability distribution of their effective numbers (Ne), we found that the actual number (Na) of the fluorophores is in linear correlation with Ne, with correction factors of 1.8 and 1.2 in measurements using linearly and circularly polarized lights, respectively. We determined Na=8±1 for 28 nm FND particles prepared by 3 MeV proton irradiation. [ABSTRACT FROM AUTHOR]