We have developed a photothermal method for far-field optical detection of nanometer-sized metal particles, combining high-frequency modulation and polarization interference contrast. We can image gold colloids down to 5 nm in diameter, with a signal-to-noise ratio higher than 10. This is a considerable improvement over commonly used optical methods based on resonance plasmon scattering which, for background reasons, are limited to particles of more than about 40 nm in diameter. We also show that in addition to its intrinsic sensitivity, our photothermal method is totally insensitive to non-absorbing scatterers as 10 nm nanoparticles can be imaged in cells.

Date Published: 19 June 2003
PDF: 5 pages
Proc. SPIE 4962, Manipulation and Analysis of Biomolecules, Cells, and Tissues, (19 June 2003); doi: 10.1117/12.485711

Published in SPIE Proceedings Vol. 4962:
Manipulation and Analysis of Biomolecules, Cells, and Tissues
Dan V. Nicolau; Joerg Enderlein; Robert C. Leif; Daniel L. Farkas, Editor(s)