P. Kusch¹, J.A. Arcos Pareja¹, A. Tsarapkin², V. Deinhart², K. Harbauer³, K. Hoeflich², and S. Reich¹

Published in:

Nano Lett., vol. 24, no. 40, pp. 12406−12412, doi:10.1021/acs.nanolett.4c02826 (2024).

Abstract:

Near-field optical microscopy and spectroscopy provide high-resolution imaging below the diffraction limit, crucial in physics, chemistry, and biology for studying molecules, nanoparticles, and viruses. These techniques use a sharp metallic tip of an atomic force microscope (AFM) to enhance incoming and scattered light by excited near-fields at the tip apex, leading to high sensitivity and a spatial resolution of a few nanometers. However, this restricts the near-field orientation to out-of-plane polarization, limiting optical polarization choices. We introduce double tips that offer in-plane polarization for enhanced imaging and spectroscopy. These double tips provide superior enhancement over single tips, although with a slightly lower spatial resolution (∼30 nm). They enable advanced studies of nanotubes, graphene defects, and transition metal dichalcogenides, benefiting from polarization control. The double tips allow varied polarization in tip-enhanced Raman scattering and selective excitation of transverse-electric and -magnetic polaritons, expanding the range of nanoscale samples that can be studied.

Keywords:

s-SNOM, TERS, TEPL, in-plane excitation, double tips.

© 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0.

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