title: Optical trapping calculations for metal nanoparticles. Comparison with experimental data for Au and Ag spheres.
abstract: We calculate the optical forces on Au and Ag nanospheres through a procedure based on the Maxwell stress tensor. We compare the theoretical and experimental force constants obtained for gold and silver nanospheres finding good agreement for all particles with r < 80 nm. The trapping of the larger particles recently demonstrated in experiments is not foreseen by our purely electromagnetic theory based on fixed dielectric properties. Since the laser power produces a heating that may be large for the largest spheres, we propose a model in which the latter particles are surrounded by a steam bubble. This model foresees the trapping of these particles and the results turn out to be in reasonable agreement with the experimental data.
authors.affiliation: Dipartimento di Fisica della Materia e Ingegneria Elettronica, Università di Messina, Messina, Italy.
authors.forename: Rosalba
authors.initials: R
authors.lastname: Saija
authors.forename: Paolo
authors.initials: P
authors.lastname: Denti
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Borghese
authors.forename: Onofrio M
authors.initials: OM
authors.lastname: Maragò
authors.forename: Maria Antonia
authors.initials: MA
authors.lastname: Iatì
mesh_terms: D003198:Computer Simulation; D006046:Gold / Q000737:chemistry* / Q000528:radiation effects*; D008027:Light; D008956:Models, Chemical; D054118:Nanospheres / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D052898:Optical Tweezers; D012834:Silver / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D012834:Silver; D006046:Gold