Near-field Raman spectroscopy using a tetrahedral SNOM tip

Klein, Susanne; Reichert, Joachim; Fuchs, Harald; Fischer, Ulrich Christian

doi:10.1117/12.662561

Cited by 5 publications

(5 citation statements)

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“…The numerical calculations also show how a dipole source at the apex of the tip leads to a highly directional radiation into the body of the tip. They thus show how the radiation of a molecule into the T-tip can be used as a highly efficient pathway for signal detection in near-field optical microscopy and spectroscopy such as tip enhanced Raman Spectroscopy [10,11]. The radiation into a narrow angular range facilitates the collection of the signal which would otherwise only be possible with optics of a high numerical aperture.…”

Section: Discussion Of the Results Of The Numerical Investigationsmentioning

confidence: 99%

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Superfocussing in a metal-coated tetrahedral tip by dimensional reduction of surface-to edge-plasmon modes

et al. 2008

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International audienceMetal-coated dielectric tetrahedral tips (T-tip) have long been considered to be interesting structures for the confinement of light to nanoscopic dimensions, and in particular as probes for scanning near-field optical microscopy. Numerical investigations using the Finite-Difference Time-Domain (FDTD) method are used to explore the operation of a T-tip in extraction mode. A dipole source in close proximity to the apex excites the tip, revealing the field evolution in the tip, the resulting edge and face modes on the metal-coated surfaces, and the coupling from these modes into highly directional radiation into the dielectric interior of the tip. These results are the starting point for illumination-mode numerical investigations by a Volume Integral equation method, which compute the field distribution that develops in a T-tip when a Gaussian beam is incident into the tip, and which show that a highly confined electric field is produced at the apex of the tip. The process of light confinement can be considered as a superfocussing effect, because the intensity of the tightly confined light spot is significantly higher than that of the focussed yet much wider incident beam. The mechanism of superfocussing can be considered as a dimensional reduction of surface plasmon modes, where an edge plasmon is the most important link between the waveguide-modes inside the tip and the confined near field at the ape

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Section: Discussion Of the Results Of The Numerical Investigationsmentioning

confidence: 99%

“…Even higher resolution, on the order of 10 nm, was obtained in SNOM images of the granular structure of metal films [3,7,8] and of the domain structure of dye monolayers adsorbed to a metal substrate [9]. Recently a T-tip was also successfully used as a probe for tip-enhanced Raman spectroscopy [10,11].…”

Section: Introductionmentioning

confidence: 99%

Superfocussing in a metal-coated tetrahedral tip by dimensional reduction of surface-to edge-plasmon modes

et al. 2008

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“…These evidences for a highly confined tip excitation led us to the idea to use these tips as probes for TERS. 11 We also chose this tip because we think it has interesting options for TERS, but the experiments described here on plasmon mediated TERS could as well have been made with a solid metal tip.…”

Section: Surface Plasmon Mediated Tip Enhanced Raman Scatteringmentioning

confidence: 99%

“…1, with an auxiliary scanning tunneling microscope mode for distance control. 10,11 A tetrahedral glass fragment is used as a transparent body of our SNOM tip ͑T-tip͒. It is coated with a 50 nm thick gold film.…”

Section: Surface Plasmon Mediated Tip Enhanced Raman Scatteringmentioning

confidence: 99%

Surface plasmon mediated tip enhanced Raman scattering

Bortchagovsky

Klein

Fischer

2009

Applied Physics Letters

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The Raman signal can be strongly increased for molecules deposited on a thin metal film in a configuration where the emission of the Raman signal into a glass support of the film is mediated by leaky surface plasmons (SPs). Here we show that SP provides an efficient pathway to detect tip enhanced Raman scattering (TERS). Based on this result, we suggest a new edge plasmon mediated TERS configuration. Plasmon modes on metal covered edges of a dielectric tetrahedral tip couple to a highly directional beam of light into the dielectric body of the tip as a pathway for signal detection.

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“…Among the various experimental techniques a most promising approach is the use of optical nearfield probes in the form of gold-coated glass tips acting both as one of the anchor points for a single molecule attached as usual via thiolate bonds and, at the same time, as a nano light source operating just at the tip apex where the molecule is attached. [31,32] In summary, we carried out an extensive ab initio simulation study of mechanical, optical, and opto-mechanical switching of a dithioazobenzene bridge between two gold electrodes to elucidate the switching properties of chromophores embedded in junctions. We find that purely optical switching cycles are mechanically hindered due to tip-induced constraints.…”

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confidence: 99%