Mapping the polarization pattern of plasmon modes reveals nano-particle symmetry
We study the wavelength and polarization dependent plasmon resonances of single silver and gold nanorods, triangles, cubes, and dimerswith a novel single particle spectroscopy method (RotPOL). In RotPOL, a rotating wedge-shaped polarizer encodes the full polarization informationof each particle within one image. This reveals the symmetry of the particles and their plasmon modes, allows analyzing inhomogeneoussamples and the monitoring of particle shape changes during growth in situ.
'Mapping the polarization pattern of plasmon modes reveals nano-particle symmetry'
O. Schubert, J. Becker, L. Carbone, Y. Khalavka, T. Provalska, I. Zins, and C. Sönnichsen
The Optimal Aspect Ratio of Gold Nanorods for Plasmonic Bio-sensing
The plasmon resonance of metal nanoparticlesshifts upon refractive index changes of the surroundingmedium through the binding of analytes. The use of thisprinciple allows one to build ultra-small plasmon sensorsthat can detect analytes (e.g., biomolecules) in volumesdown to attoliters. We use simulations based on theboundary element method to determine the sensitivity ofgold nanorods of various aspect ratios for plasmonicsensors and find values between 3 and 4 to be optimal.Experiments on single particles confirm these theoreticalresults. We are able to explain the optimum by showing acorresponding maximum for the quality factor of theplasmon resonance.
'The Optimal Aspect Ratio of Gold Nanorods for Plasmonic Bio-sensing'
J. Becker, A. Trügler, A. Jakab, U. Hohenester, C. Sönnichsen