Scattering from noble metallic nanoparticles with specific structures are strongly depolarized in contrast to dielectric particles. The effect depends on the shape and symmetry of the nanoparticles and can be explained by induced plasmonic multi-resonances along different axes of symmetry. In our experiments we found that the scattering from 'nanorod' structures of silver is more polarized than globular colloidal silver nanostructures. The depolarized scattering can be tuned to the near-infrared region by using proportionate mixture of the colloids and nanorods. We demonstrate this effect in solution as well as in polymer films where nanoparticles were immobilized. This phenomenon of depolarized scattering is promising for designing dye-less sensing devices useful in diagnostics. We show scattering polarization profile from asymmetric nanostructures changes during their aggregation. Modulating the rate of aggregation of these nanostructures by 'receptor - ligand'-like interactions can be successfully utilized for sensitive 'dye-less' diagnostics.

Date Published: 12 February 2010
PDF: 7 pages
Proc. SPIE 7574, Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications VII, 75740V (12 February 2010); doi: 10.1117/12.841392

Published in SPIE Proceedings Vol. 7574:
Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications VII
Alexander N. Cartwright; Dan V. Nicolau, Editor(s)