Multiple scattering calculations of the electromagnetic force and the potential energy exerted by an evanescent field on a nanometric cylinder over a dielectric interface, as well as by a propagating Gaussian beam, are carried out. These calculations constitute a model that describes the gradient, scattering, and absorption components of the force in an elongated particle. The attractive or repulsive nature of the force is strongly dependent on the polarization of the incident field for a metallic particle, whereas a dielectric particle is only weakly attracted to high-intensity regions. Excitation of plasmon resonance in a metallic particle enhances both the scattering and the absorption components of the force, whereas it diminishes the gradient-force component.
© 2002 Optical Society of America
(170.4520) Medical optics and biotechnology : Optical confinement and manipulation
(240.6680) Optics at surfaces : Surface plasmons
(260.2110) Physical optics : Electromagnetic optics
(260.5740) Physical optics : Resonance
(290.4210) Scattering : Multiple scattering
J. R. Arias-Gonzàlez and M. Nieto-Vesperinas, "Radiation pressure over dielectric and metallic nanocylinders on surfaces: polarization dependence and plasmon resonance conditions," Opt. Lett. 27, 2149-2151 (2002)