Preparation of gold tips suitable for tip-enhanced Raman spectroscopy and light emission by electrochemical etching

Ren, Bin; Picardi, Gennaro; Pettinger, Bruno

doi:10.1063/1.1688442

Cited by 338 publications

(287 citation statements)

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“…The STM tip was in most cases prepared from a gold wire of 0.25 mm diameter by electrochemical etching in a 1 : 1 mixture of ethanol and fuming HCl, yielding typical tip radii of about 30-60 nm. 33,34 STM images were recorded with either Au or Ir tips and showed that the surfaces studied were fairly smooth, exhibiting essentially only monoatomic steps.…”

Section: Methodsmentioning

confidence: 99%

“…32 We noticed that for such a giant enhancement particular tips are required, presumably tips that have a smooth surface and a sharp apex (radius <50 nm). Therefore, substantial effort has been devoted to elaborating procedures for the easy production of suitable tips, based on electrochemical etching techniques as described in a paper by Ren et al 33 We are now able routinely to fabricate tips with an apex radius of R tip Ä 30 nm. …”

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confidence: 99%

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Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Pettinger

Ren

Picardi

et al. 2005

J Raman Spectroscopy

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Tip-enhanced Raman spectroscopy (TERS) was investigated with malachite green isothiocyanate adsorbed at an Au(111) surface. TERS is based on the excitation of localized surface plasmons in the tip apex, producing strongly enhanced electromagnetic fields. The key conditions for giant TERS are sideillumination of the tip, well-prepared single-crystalline surfaces and sharp, smooth gold tips. A TERS enhancement of about 6 × 10 6 has been observed for dye molecules adsorbed at the Au(111) substrate in a region of about 50 nm diameter beneath the tip. This corresponds to a 2500-fold increase in the light intensity at the Au(111)/air interface, which in addition causes fast but local bleaching of the dye. This bleaching behavior was analyzed in detail, giving direct insight into the strength and size of the enhanced field. In addition, the bleaching constant was higher for MGITC in an unperturbed environment than for MGITC in an environment that had been substantially bleached. The MGITC spectra were also different for these two cases. Copyright  2005 John Wiley & Sons, Ltd.KEYWORDS: apertureless scanning near-field optical microscopy; gold(111); tip-enhanced Raman spectroscopy; malachite green isothiocyanate; near-field enhancement INTRODUCTIONThe general use of Raman spectroscopy for surface studies is an old dream of surface scientists. However, with differential Raman cross-sections of the order of d /d ³ 10 31 -10 28 cm 2 sr 1 , surface studies were out of reach in general, although a (small) number of attempts were made to apply (normal) Raman scattering for the investigation of well-defined surfaces.Ł Correspondence to: Bruno Pettinger, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany. E-mail: pettinger@fhi-berlin.mpg. Recently, a new approach has been developed, denoted tip-enhanced Raman spectroscopy (TERS), in some cases also called 'apertureless scanning near-field optical microscopy (SNOM)'. 1 With the advent of TERS, the above-mentioned dream is now becoming a reality. 1 -12 TERS is a particular promising variant of SERS, the well-studied field of surface-enhanced Raman scattering spectroscopy. The latter requires roughened surfaces at which two cooperative enhancement mechanisms for Raman scattering are working. Roughened surfaces can support the excitation of localized surface plasmons leading to the so-called 'electromagnetic enhancement' and provide the peculiar adsorption sites at which the so-called 'chemical enhancement' is operative. In the literature, a large range of (total) enhancement factors are given, starting with the 10 6 -fold enhancement found for pyridine on roughened silver electrodes 13 up to the giant 10 12 -10 14 -fold enhancement reported more recently by Nie and Emory 14 and Kneipp et al. 15 for dyes at colloidal particles. In the latter case, the authors claim to have reached single-molecule detection sensitivity. However, in all these cases the general drawback of SERS investigations remains: the surface enhancement (in particular its ...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Pettinger

Ren

Picardi

et al. 2005

J Raman Spectroscopy

Self Cite

142

154

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“…The smoothness of surface is important to avoid forming multiple contacts and contamination by carbon. 21 …”

Section: Design and Construction Of The Cat Rigmentioning

confidence: 99%

“…20 The etching of gold occurs via reduction-oxidation reactions aided by dc bias in an acid solution. 21 For the best performance in PCS, the procedure is optimized to produce a thin, long, smooth, uniform and clean gold tip, as shown in Fig. 2.…”

Section: Design and Construction Of The Cat Rigmentioning

confidence: 99%

Construction of a Cantilever-Andreev-Tunneling rig and its applications to superconductors

Park

Greene

2006

Review of Scientific Instruments

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A technique for point-contact spectroscopy, based on an electro-mechanical mechanism for the contact formation, has been developed. It is designed to be used in both 4 He and 3 He cryostats. The performance has been demonstrated by conductance measurements on various kinds of superconductors, including the conventional superconductor Nb, the two-band superconductor MgB2, and the heavy-fermion superconductor CeCoIn5. Characteristic conductance spectra obtained prove this technique is useful for the investigation of the superconducting order parameter. Advantages of this technique such as its simplicity and versatility are described.

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“…Small molecules have only become visible once the fabrication methods for producing extremely sharp Au and Ag tips became available. [29] Besides sharpening the tip, another way to increase the enhancement is to increase the wavelength of the illumination, since the sharpness refers to the relative dimension between the radius of curvature of the tip apex and the wavelength. However, to the best of our knowledge, nothing has yet been reported in this direction because the sensitivity of the detectors is generally much lower in the IR regime than in the optical regime.…”

Section: Tip Sharpness Influences the Field Enhancementmentioning

confidence: 99%

Local field enhancement of an infinite conical metal tip illuminated by a focused beam

Zhang

Cui

Martin

2009

J Raman Spectroscopy

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We present a systematic numerical investigation of conical metal tips which are commonly used in tip-enhanced Raman spectroscopy (TERS). Different from previous studies, we focus on how the tip length and the illumination condition influence the local field enhancement at the tip apex, and provide a useful reference for real experiments. In particular, we show that the type of illumination has a dramatic influence on the field enhancement: a localized illumination spot -as used in experiments -producing a very different response than a plane wave illumination -as usually used in previous models. Also, the effect of the different geometrical parameters, such as the sharpness of the tip apex and the cone angle, provides guidance to optimize the tip design. Finally, we investigate the influence of the substrate and compare numerical data with results deduced from a simplified model, finding good agreement. This brings new insights into the enhancement mechanism of TERS.

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Preparation of gold tips suitable for tip-enhanced Raman spectroscopy and light emission by electrochemical etching

Cited by 338 publications

References 27 publications

Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Construction of a Cantilever-Andreev-Tunneling rig and its applications to superconductors

Local field enhancement of an infinite conical metal tip illuminated by a focused beam

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