抄録
We introduce a novel technique for the quantitative analysis of plasmonic trapping potentials experienced
by a nanometer-sized particle. Our experimental results show that these potentials have nanoscale spatial
structures that reflect the near-field landscape of the metal nanostructure. The trap stiffness of plasmonic
trapping can be enhanced by three orders of magnitude compared to conventional far-field trapping. We
also demonstrated super-resolution optical trapping by observing double potential wells with 80-nm
separation, which was realized by a gold double-nonogap structure. In addition, we analyzed the
nanoscale spatial profiles of plasmonic fields within a nanogap, which exhibit complicated fine structures
created by the constructive and destructive interferences of dipolar, quadrupolar, and higher-order
multipolar plasmonic modes. The nanoprofile can be drastically changed by controlling the excitation
optical system, which is applicable to the dynamic nanomanipulation of single molecules and molecular
assemblies.
