Surface-enhanced optical microscopy

Wessel, John E.

doi:10.1364/josab.2.001538

Cited by 443 publications

(276 citation statements)

References 9 publications

Supporting

Mentioning

271

Contrasting

Unclassified

Order By: Relevance

“…Local resonances of the surface topology are believed to be responsible for the field enhancement effect [3]. While resonances are generally spatially randomly distributed on metallic films [4], they can be localized at the apex of a sharp metallic tip [5]. The enhancement at such a structure arises from a combination of an electrostatic rod effect and surface plasmon oscillations.…”

Section: Introductionmentioning

confidence: 99%

Applications of field-enhanced near-field optical microscopy

2004

View full text Add to dashboard Cite

Metal nanostructures such as sharp tips can enhance emission yields through shape-induced local field enhancement. The enhancement originates from two mechanisms: surface plasmons and electrostatic lightening rod effects. We present fluorescence imaging using the strong local field created at the apex of a gold tip and demonstrate optical resolution of 25 nm: The enhancement effect gives also rise to photoemission from the tip itself. Measured spectra of the tip emission show a broad band continuum together with a second-harmonic peak. Both continuum and secondharmonic are confined at the apex of the tip. We find that, depending on the spectral position, the photoluminescence originates either from intraband or from interband transitions. The nonlinear response can be described by a single dipole oscillating at the second-harmonic frequency and oriented along the tip axis. These unique properties can be used to map focal fields distributions. r

show abstract

Section: Introductionmentioning

confidence: 99%

Applications of field-enhanced near-field optical microscopy

2004

View full text Add to dashboard Cite

show abstract

“…Surface enhanced Raman scattering (SERS), induced by nanometer-sized metal structures, has been shown to provide enormous enhancement factors of up to 10 15 allowing for Raman spectroscopy even on the single molecule level [2,3]. Controlling SERS with a sharp metal tip which is raster scanned over a sample surface has been proposed [1,4], and near-field Raman enhancement has been experimentally demonstrated [5][6][7][8][9]. Here, we show the chemical specificity of this near-field technique and demonstrate an unprecedented spatial resolution.…”

mentioning

confidence: 99%

High-Resolution Near-Field Raman Microscopy of Single-Walled Carbon Nanotubes

et al. 2003

View full text Add to dashboard Cite

We present near-field Raman spectroscopy and imaging of single isolated single-walled carbon nanotubes with a spatial resolution of 25 nm. The near-field origin of the image contrast is confirmed by the measured dependence of the Raman scattering signal on tip-sample distance and the unique polarization properties. The method is used to study local variations in the Raman spectrum along a single single-walled carbon nanotube. DOI: 10.1103/PhysRevLett.90.095503 PACS numbers: 61.46.+w, 07.79.-v, 78.30.Na, 78.67.Ch Recent rapid advances in nanotechnology and nanoscience are largely due to our newly acquired ability to measure and manipulate individual structures on the nanoscale. Among the new methods are scanning probe techniques, optical tweezers, and high-resolution electron microscopes. Recently, a near-field optical technique has been demonstrated which allows spectroscopic measurements with 20 nm spatial resolution [1]. The method makes use of the strongly enhanced electric field close to a sharp metal tip under laser illumination and relies on the detection of two-photon excited fluorescence. However, fluorescence imaging requires a high fluorescence quantum yield of the system studied or artificial labeling with fluorophores. Furthermore, fluorescence quenching by the metal tip competes with the local field enhancement effect and therefore limits the general applicability. On the other hand, Raman scattering probes the unique vibrational spectrum of the sample and directly reflects its chemical composition and molecular structure. A main drawback of Raman scattering is the extremely low scattering cross section which is typically 14 orders of magnitude smaller than the cross section of fluorescence. Surface enhanced Raman scattering (SERS), induced by nanometer-sized metal structures, has been shown to provide enormous enhancement factors of up to 10 15 allowing for Raman spectroscopy even on the single molecule level [2,3]. Controlling SERS with a sharp metal tip which is raster scanned over a sample surface has been proposed [1,4], and near-field Raman enhancement has been experimentally demonstrated [5][6][7][8][9]. Here, we show the chemical specificity of this near-field technique and demonstrate an unprecedented spatial resolution.Single-walled carbon nanotubes (SWNTs) have been the focus of intense interest due to a large variety of potential nanotechnological applications. The unique properties of SWNTs arise from their particular onedimensional structure which is directly linked to the characteristic Raman bands. Raman scattering on SWNTs has been studied intensively in the literature (see, e.g., Refs. [10 -13]) and Raman enhancements of up to 10 12 have been reported for tubes in contact with fractal silver colloidal clusters [14]. In this Letter, nearfield Raman imaging of SWNTs is demonstrated using a sharp silver tip as a probe. We show, for the first time, that single isolated SWNTs can be detected optically with a spatial resolution better than 30 nm. This high-resolution capability is ap...

show abstract

“…In 1985, John Wessel published a paper outlining the concept of using a submicron sized metal particle as a probe for near field microscopy [Wessel, 1985].…”

Section: 2: Near-field Microscopymentioning

confidence: 99%

Symmetric Near-Field Probe Design and Comparison to Asymmetric Probes

Doughty

2000

View full text Add to dashboard Cite

Tip Enhanced Near-field Optical Microscopy (TENOM) is a method for optically imaging at resolutions far below the diffraction limit. This technique requires optical nano-probes with very specialized geometries, in order to obtain large, localized enhancements of the electromagnetic field, which is the driver behind this imaging method. Traditional methods for the fabrication of these nano-probes involve electrochemical etching and subsequent FIB milling. However, this milling process is non-trivial, requiring multiple cuts on each probe. This requires multiple rotations of the probe within the FIB system, which may not be possible in all systems, meaning the sample must be removed from vacuum, rotated by hand and placed back under vacuum. This is time consuming and costly and presents a problem with reproducibility. The method presented here is to replace multiple cuts from a side profile with a small number of cuts from a top down profile. This method uses the inherent imaging characteristics of the FIB, by assigning beam dwell times to specific locations on the sample, through the use of bitmap images. These bitmaps are placed over the sample while imaging and provide a lookup table for the beam while milling.These images are grayscale with the color of each pixel representing the dwell time at that pixel. This technique, combined with grayscale gradients, can provide probes with a symmetric geometry, making the system polarization independent.ii Dedication This work is dedicated to every person who never has no in their heart. Those people who face all odds and persevere. You are the people who make the world turn. Never give up, your dreams can indeed be realized.

show abstract

Surface-enhanced optical microscopy

Cited by 443 publications

References 9 publications

Applications of field-enhanced near-field optical microscopy

Applications of field-enhanced near-field optical microscopy

High-Resolution Near-Field Raman Microscopy of Single-Walled Carbon Nanotubes

Symmetric Near-Field Probe Design and Comparison to Asymmetric Probes

Contact Info

Product

Resources

About