Nonresonant excitation of plasmon surface polaritons on silver gratings in air and in electrolyte

Abstract

The emission of elastically scattered light from radiative plasmonsurfacepolariton (PSP) modes of a silvergrating has been observed when the grating is struck by a laser beam at an angle that does not excite PSP modes directly. This nonresonant angular excitation occurs through the involvement of surface roughness, which provides additional momentum matching sources. Two types of experiments are described, the first for gratings in air and the second for a grating electrode immersed under potentiostatic control in an aqueous electrolyte. Roughness scattering increased greatly upon immersion and a new peak not associated with PSP modes was observed in the p→p and s→sscattering channels.