Open AccessOptical trapping calculations for metal nanoparticles Comparison with experimental data for Au and Ag spheres
Author(s) -
Rosalba Saija,
P. Denti,
Ferdinando Borghese,
Onofrio M. Maragò,
Maria Antonia Iatı̀
Publication year - 2009
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.17.010231
Subject(s) - spheres , materials science , trapping , dielectric , optical tweezers , optical force , maxwell stress tensor , nanoparticle , optics , metal , molecular physics , mie scattering , nanotechnology , condensed matter physics , cauchy stress tensor , physics , classical mechanics , light scattering , optoelectronics , scattering , ecology , astronomy , metallurgy , biology
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.