title: Photothermal heterodyne imaging of individual nonfluorescent nanoclusters and nanocrystals.
abstract: We introduce a new, highly sensitive, and simple heterodyne optical method for imaging individual nonfluorescent nanoclusters and nanocrystals. A 2 order of magnitude improvement of the signal is achieved compared to previous methods. This allows for the unprecedented detection of individual small absorptive objects such as metallic clusters (of 67 atoms) or nonluminescent semiconductor nanocrystals. The measured signals are in agreement with a calculation based on the scattering field theory from a photothermal-induced modulated index of refraction profile around the nanoparticle.
authors.affiliation: Centre de Physique Moléculaire Optique et Hertzienne, CNRS (UMR 5798) et Université Bordeaux I, 351, cours de la Libération, 33405 Talence Cedex, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Berciaud
authors.forename: Laurent
authors.initials: L
authors.lastname: Cognet
authors.forename: Gerhard A
authors.initials: GA
authors.lastname: Blab
authors.forename: Brahim
authors.initials: B
authors.lastname: Lounis