title: Adiabatic nanofocusing scattering-type optical nanoscopy of individual gold nanoparticles.
abstract: We explore imaging of local electromagnetic fields in the vicinity of metallic nanoparticles using a grating-coupled scattering-type near-field scanning optical microscope. In this microscope, propagating surface plasmon polariton wavepackets are launched onto smooth gold tapers where they are adiabatically focused toward the nanometer-sized taper apex. We report two-dimensional raster-scanned optical images showing pronounced near-field contrast and demonstrating sub-30 nm resolution imaging of localized surface plasmon polariton fields of spherical and elliptical nanoparticles. By comparison to three-dimensional finite-difference time domain simulations, we conclude that virtually background-free near-field imaging is achieved. The microscope combines deep subwavelength resolution, high local field intensities and a straightforward imaging contrast, making it interesting for a variety of applications in linear and nonlinear nanospectroscopy.
authors.affiliation: Institut für Physik, Carl von Ossietzky Universität, 26111 Oldenburg, Germany.
authors.forename: Diyar
authors.initials: D
authors.lastname: Sadiq
authors.forename: Javid
authors.initials: J
authors.lastname: Shirdel
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Lee
authors.forename: Elena
authors.initials: E
authors.lastname: Selishcheva
authors.forename: Namkyoo
authors.initials: N
authors.lastname: Park
authors.forename: Christoph
authors.initials: C
authors.lastname: Lienau
mesh_terms: D006046:Gold / Q000737:chemistry*; D007089:Image Enhancement / Q000379:methods*; D008422:Materials Testing / Q000379:methods; D020527:Microscopy, Scanning Probe / Q000379:methods*; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D006046:Gold