Tuning Localized Surface Plasmon Resonance in Scanning Near-Field Optical Microscopy Probes

Abstract

A reproducible route for tuning localized surface plasmon resonance in scattering type near-field optical microscopy probes is presented. The method is based on the production of a focused-ion-beam milled single groove near the apex of electrochemically etched gold tips. Electron energy-loss spectroscopy and scanning transmission electron microscopy are employed to obtain highly spatially and spectroscopically resolved maps of the milled probes, revealing localized surface plasmon resonance at visible and near-infrared wavelengths. By changing the distance L between the groove and the probe apex, the localized surface plasmon resonance energy can be fine-tuned at a desired absorption channel. Tip-enhanced Raman spectroscopy is applied as a test platform, and the results prove the reliability of the method to produce efficient scattering type near-field optical microscopy probes.

Raman spectroscopy: techniques and applications in the life sciences

“…Other approaches for TERS tip fabrication include photochemical nanoparticle growth localized to the tip using a nanoparticleseed precursor solution in-situ [353], the fabrication of solid silver cantilevers to avoid loss of enhancement due to wear of the silver films [354], and focused-ion-beam milling of grooves into a metallic wire to engineer specific tip-plasmon resonances [355,356]. Recently nanoparticle attachment methods using dielectrophoresis have also been explored by several groups [357][358][359].…”

“…Copyright 2007 American Chemical Society. ), (m) tunable Au TERS tip prepared by focused-ion-beam milling [356] (Reprinted (adapted) with permission. Copyright 2008 American Chemical Society.).…”

A classical description of subnanometer resolution by atomic features in metallic structures

“…[9][10][11][12][13] An improvement regarding resolution can be obtained by further substructuring these near-field probes. [14][15][16] Considering the "crude" dimensions of plasmonic structures, as for instance obtained from SEM, the field confinement in these structures reaches only a few nanometers at best and cannot directly explain the recently experimentally demonstrated lateral resolution below 1 nm. [17][18][19][20][21] Additional localization of electromagnetic fields might be related to the presence of much smaller (ultimately down to a single atom) features, usually not considered when describing the morphology of nanostructures in generally applied models.…”

Broadband Optical Absorption Caused by the Plasmonic Response of Coalesced Au Nanoparticles Embedded in a TiO2 Matrix

“…[35][36][37][38][39][40][41] More recently, the knowledge acquired about plasmonic materials is being studied for the development of chemical and biological (LSPR) sensors. [42][43][44][45][46][47][48][49][50][51] . Furthermore, taking the advantage of Raman scattering from molecules located on top of plasmonic materials, the Surface-Enhanced Raman Scattering (SERS) effect is often used in chemical sensing, since it may allow single molecule detection.…”