Plasmonic optical antenna design for performing tip-enhanced Raman spectroscopy and microscopy

Kharintsev, Sergey S.; Hoffmann, Gerhard; Фишман, А. И.; Салахов, М. Х.

doi:10.1088/0022-3727/46/14/145501

Cited by 36 publications

(40 citation statements)

References 44 publications

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“…In recent years controlled nanostructuring of the tip apex with a distinct subwavelength-size metallic feature has been explored in order to engineer and tune a plasmonic optical antenna * Email: jjb12@cam.ac.uk; Site: www.np.phy.cam.ac.uk precisely at the apex and better incorporate more localised multipolar plasmons [16][17][18][19][20][21] Scattering resonances in the visible-NIR spectrum have been directly measured on a subset of these [25,26,29] while other reports use improvements in the field enhancement as a measurement of antenna quality [20,21,28]. In such cases the field enhancement has been attributed to give improvements by an order of magnitude through plasmon excitation [20,23,24,29].…”

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confidence: 99%

Understanding the plasmonics of nanostructured atomic force microscopy tips

Sanders

Bowman

Zhang

et al. 2016

Applied Physics Letters

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Structured metallic tips are increasingly important for optical spectroscopies such as tip-enhanced Raman spectroscopy (TERS), with plasmonic resonances frequently cited as a mechanism for electric field enhancement. We probe the local optical response of sharp and spherical-tipped atomic force microscopy (AFM) tips using a scanning hyperspectral imaging technique to identify plasmonic behaviour. Localised surface plasmon resonances which radiatively couple with far-field light are found only for spherical AFM tips, with little response for sharp AFM tips, in agreement with numerical simulations of the near-field response. The precise tip geometry is thus crucial for plasmonenhanced spectroscopies, and the typical sharp cones are not preferred.Within the last decade nano-optics has benefited from the advent of metallic tip-based near-field enhancement techniques such as TERS and scanning near-field microscopy (SNOM), leading to successes in single molecule detection [1] and spatial mapping of chemical species [2]. Despite their high spatial resolution and scanning capabilities, there remains confusion about the plasmonic response of metallic tips. Tip systems built on AFM probes can exhibit electric field enhancements close to 100 at the apex (Raman enhancements up to 10 8 ) [2], due to a combination of plasmonic localisation and a non-resonant lightning rod effect. The factors determining a tip's ability to enhance the near-field include the experimental excitation/collection geometry, tip sharpness, surface metal morphology, and constituent material.Despite large measured near-field enhancements, the standard sharp AFM tip geometry does not support radiative plasmons. The extended (∼20 µm) size and single curved metal-dielectric interface of an AFM tip supports only weakly confined localised surface plasmons (LSPs) [3] and propagating surface plasmon polaritons (SPPs), which may be localised by adiabatic nanofocussing [4][5][6][7][8][9]. Lack of a dipole moment means that neither LSPs or SPPs strongly couple with radiative light in the same manner as multipolar plasmons in subwavelength nanoparticles [3]. For this reason, the tip near-field is often excited with evanescent waves [10] or via nanofabricated gratings [6] to access the opticallydark SPPs, with resonant scattering of evanescent waves [11][12][13], resonances in the TERS background [14,15] and depolarised scattering images [16] providing evidence for localised plasmon excitation. For Au tips such plasmon resonances are typically found between 600-800 nm.Improvements in enhancement are often found in roughened tips with grains acting as individual nanoantennae for more confined LSPs, however this approach lacks reproducibility [16]. In recent years controlled nanostructuring of the tip apex with a distinct subwavelength-size metallic feature has been explored in order to engineer and tune a plasmonic optical antenna * Email: jjb12@cam.ac.uk; Site: www.np.phy.cam.ac.uk precisely at the apex and better incorporate more localised multipolar plasmons [16...

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confidence: 99%

Understanding the plasmonics of nanostructured atomic force microscopy tips

Sanders

Bowman

Zhang

et al. 2016

Applied Physics Letters

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“…Without loss of generality we use a solution of fuming hydrochloric acid (HCl, 37%) and ethanol (C 2 H 5 OH, 96%) in a volume proportion of 1: 1 as an etching electrolyte [11][12][13]. − [11,22] which block an access for Cl − anions to WE in the vicinity of an etchant meniscus. This value corresponds to an electrode potential of 1.68 V for gold at which a leading corrosion mechanism Au ↔ Au + + e − takes place [21].…”

Section: Dc-pulsed Voltage Etching With Self-tuneable Duty Cyclementioning

confidence: 99%

“…This originates from the capacitance model or the Maxwell stress tensor in the case of a non-charged interfacial surface [23]. Thus, one of the ways to overcome blocking corrosion because of the passivation layer is the dcpulsed voltage etching method [22]. With this, a voltage-driven meniscus performs oscillations along the gold wire and, therefore, mechanical mixing of the solution near the interface takes place.…”

Section: Dc-pulsed Voltage Etching With Self-tuneable Duty Cyclementioning

confidence: 99%

“…In other words, upward/downward motion of the meniscus speeds up the diffusion of corrosion products. It has been found [22,24] that the etching current kinetics is followed by the fractional Brownian motion model and satisfies a power law with a complex fractional exponent, namely, A self-similar behaviour of the etching current during the etching allows us to introduce a handling parameter η as a ratio of a current value i I…”

Section: Dc-pulsed Voltage Etching With Self-tuneable Duty Cyclementioning

confidence: 99%

“…Electrochemical etching is widely used as a low-cost, simple and reliable fabrication tool for designing plasmonic optical conical nanoantennas with a high yield of >90% [21,22]. A drawback of this method is related to optimization of a large number of parameters such as the chemical nature of etching electrolyte, electrode arrangement, an applied voltage shape, etching timing, a cutoff current and others.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical design of plasmonic nanoantennas for tip-enhanced optical spectroscopy and imaging performance

Kharintsev

Алексеев

Vasilchenko

et al. 2015

Opt. Mater. Express

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Optical nanoantennas play a crucial role in controlling near-fields on the nanoscale and being counterparts of commonly used conventional optical components such as lens, prisms, gratings, etc. for shaping the wavefront of light in the far-field. In this paper we highlight a dc-pulsed voltage electrochemical etching method with a self-tuneable duty cycle for highly reproducible design of plasmonic (metallic) nanoantennas. With the method, we introduce such concepts as design, optimization and figure-ofmerit for evaluating fabrication efficiency. The ability of the nanoantennas to enhance and localize the optical fields beyond the diffraction limit is statistically studied with Rayleigh scattering from the tip apex and tipenhanced Raman spectroscopy of a single walled carbon nanotubes bundle.

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Spectral Tuning of Plasmonic Activity in 3D Nanostructures via High‐Precision Nano‐Printing

Reisecker,

Kuhness,

Haberfehlner

et al. 2023

Adv Funct Materials

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Plasmonic nanoparticles reveal unique optical properties and are increasingly incorporated into commercial products and technologies, ranging from photovoltaics to biological and chemical sensors. Shifting and tuning their plasmonic response according to the targeted application strongly depends on the ability to control the geometry in every detail and has not been reliably demonstrated for complex 3D nano‐architectures yet. Following that motivation, it herein presents how Focused Electron Beam Induced Deposition (FEBID), a highly flexible additive 3D direct‐write technology with spatial nano‐scale precision, is used for the controlled and tunable fabrication of plasmonically active 3D nanostructures that exhibit highly concentrated, well defined and predictable local plasmonic resonances. As model systems, planar Au nanowires and 3D nano‐tips of various geometries are prepared via FEBID and plasmonically characterized via scanning transmission electron microscopy based electron energy loss spectroscopy (STEM‐EELS) mapping measurements. The findings are complemented with corresponding plasmon simulations, revealing very good agreement with experimental findings. This way, on‐demand spectral tuning of the plasmonic response becomes accessible via upfront modeling and design of suitable 3D nanostructures, to achieve customized plasmonic responses, therefore paving the way for yet unrealized plasmonic applications in 3D space.

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Plasmonic optical antenna design for performing tip-enhanced Raman spectroscopy and microscopy

Cited by 36 publications

References 44 publications

Understanding the plasmonics of nanostructured atomic force microscopy tips

Understanding the plasmonics of nanostructured atomic force microscopy tips

Electrochemical design of plasmonic nanoantennas for tip-enhanced optical spectroscopy and imaging performance

Spectral Tuning of Plasmonic Activity in 3D Nanostructures via High‐Precision Nano‐Printing

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