Experimental determination of distance and orientation of metallic nanodimers by polarization dependent Plasmon coupling

HERNÁN E. GRECCO; O.E. MARTÍNEZ

PAPERS IN PHYSICS

Papers in Physics

Año: 2010 vol. 2 p. 1 - 9

1852-4249

Live cell imaging using metallic nanoparticles as tags is an emerging technique to visualize long and highly dynamic processes due to the lack of photobleaching and high photon rate. However, the lack of excited states as compared to uorescent dyes prevents the use of resonance energy transfer and recently developed super resolution methods to measure distances between objects closer than the diraction limit. In this work, we experimentally demonstrate a technique to determine subdiraction distances based on the near eld coupling of metallic nanoparticles. Due to the symmetry breaking in the scattering cross section, not only distances but also relative orientations can be measured. Single gold nanoparticles were prepared on glass, statistically yielding a small fraction of dimers. The sample was sequentially illuminated with two wavelengths to separate background from nanoparticle scattering based on their spectral properties. A novel total internal re ection illumination scheme in which the polarization can be rotated was used to further minimize background contributions. In this way, radii, distance and orientation were measured for each individual dimer, and their statistical distributions were found to be in agreement with the expected ones. We envision that this technique will allow fast and long term tracking of relative distance and orientation in biological processes.