The local density of optical states governs an emitters lifetime and quantum yield through the Purcell effect. It can be modified by a surface plasmon electromagnetic field, but such a field has a spatial extension limited to a few hundreds of nanometers, which complicates the use of optical methods to spatially probe the emitter-plasmon coupling. Here we show that a combination of electron-based imaging, spectroscopies and photon-based correlation spectroscopy enables measurement of the Purcell effect with nanometer and nanosecond spatio-temporal resolutions. Due to the large variability of radiative lifetimes of emitters embedded in nanoparticles with inhomogeneous sizes we relied on a statistical approach to unambiguously probe the coupling between nitrogen-vacancy centers (NV^0) in nanodiamonds and surface plasmons in silver nanocubes. We quantified the Purcell effect by measuring the NV^0 excited state lifetimes in a large number of either isolated nanodiamonds or nanodiamond-nanocube dimers and demonstrated a statistically significant lifetime reduction for dimers.
@article{arxiv.1906.00388,
title = {Probing plasmon-NV$^0$ coupling at the nanometer scale with photons and fast electrons},
author = {H. Lourenço-Martins and M. Kociak and S. Meuret and F. Treussart and Yih Hong Lee and Xing Yi Ling and H. C. Chang and L. H. G. Tizei},
journal= {arXiv preprint arXiv:1906.00388},
year = {2019}
}