Far-field optical microscopy of single metal nanoparticles.
Individual noble-metal particles, with sizes ranging from a few tenths to some hundreds of nanometers, can now be detected by far-field optics. Single-particle microscopy gives access to inhomogeneity, distributions, and fluctuations, which were previously hidden in ensemble experiments. Scattering methods rely on dark-field illumination, spectral signatures of the metal particles, or both. More advanced techniques provide high sensitivity and improved selectivity with respect to other scatterers by isolating metal-specific signals, for example the refractive index change due to heating of the environment by a pump beam or the time-resolved optical response of the particle to a short pump pulse. We review and compare linear and nonlinear methods in far-field optical microscopy that have reached the single-particle regime by means of scattered light, thermal effects, photoluminescence, or nonlinear frequency generation.
van Dijk
Meindert A
MA
MoNOS, Huygens Laboratory, Universiteit Leiden, P.O. Box 9504, 2300 RA Leiden, The Netherlands.
Lippitz
Markus
M
Orrit
Michel
M