Gold nanoparticle tips for optical field confinement in infrared scattering near-field optical microscopy.
We report on the implementation of metal nanoparticles as probes for scattering and apertureless near-field optical investigations in the mid-infrared (mid-IR) spectral regime. At these wavelengths, an efficient electric-field confinement is necessary and achieved here through a gold metal nanoparticle of 80 nm in diameter (Au80-MNP) acting as the optical antenna. The Au80-MNP is attached to a standard AFM cantilever used as the spatial manipulator. When approached to a sample surface while being illuminated with an infrared beam, the Au80-MNP produces a considerably improved spatial confinement of the electric field compared to an ordinary scattering AFM tip. We demonstrate here the confinement normal to the sample surface by making use of a sample-induced phonon polariton resonance in a ferroelectric lithium niobate sample. Our experimental findings are in very good agreement with the quasistatic dipole model and show improved optical resolution via well-selected antenna particles.
Wenzel
Marc Tobias
MT
Institute of Applied Photophysics, Technische Universität Dresden, 01062 Dresden, Germany. marc.tobias.wenzel@iapp.de
Härtling
Thomas
T
Olk
Phillip
P
Kehr
Susanne C
SC
Grafström
Stefan
S
Winnerl
Stephan
S
Helm
Manfred
M
Eng
Lukas M
LM
D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D007089:Image Enhancement / Q000295:instrumentation*; D007259:Infrared Rays; D018625:Microscopy, Atomic Force / Q000295:instrumentation* / Q000379:methods; D008962:Models, Theoretical; D053758:Nanoparticles / Q000737:chemistry*; D012542:Scattering, Radiation; D013055:Spectrophotometry, Infrared / Q000295:instrumentation*; D014159:Transducers
D006046:Gold