title: Role of in-plane polarizability of the tip in scattering near-field microscopy of a plasmonic nanoparticle.
abstract: We report that a pyramid-shaped scanning probe microscopy tip has non-zero polarizability along the in-plane direction (perpendicular to the tip axis, z) at visible frequency. The in-plane polarizability enables the scattering-type scanning near-field optical microscopy (s-SNOM) to measure the in-plane field component around a plasmon-resonant nanoparticle. Because of the non-zero in-plane polarizability, the cross-polarized s-SNOM images may contain contributions from the in-plane field component of an out-of-plane plasmon mode as well as the out-of-plane field component of an in-plane mode. By comparing a scattering model and experimental s-SNOM images, we estimate the polarization anisotropies of pyramid-shaped Si-tips and metal-coated Si-tips.
authors.affiliation: Department of Chemistry, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-701, Korea.
authors.forename: Deok-Soo
authors.initials: DS
authors.lastname: Kim
authors.forename: Zee Hwan
authors.initials: ZH
authors.lastname: Kim