Low cost tips for tip-enhanced Raman spectroscopy fabricated by two-step electrochemical etching of 125 µm diameter gold wires

Tip-enhanced Raman spectroscopy (TERS) has become a well-applied technique for nanospectroscopy, allowing for single molecule sensitivity with sub-nanometer spatial resolution. The demand for efficient, reproducible and cost-effective probes for TERS is increasing. Here we report on a new electrochemical etching protocol to fabricate TERS tips starting from 125 µm diameter gold wires in a reproducible way. The process is reliable (50% of the tips have radius of curvature <35 nm, 66% <80 nm), fast (less than 2 min) and 2.5 times cheaper than the etching of standard 250 µm diameter wires. The TERS performance of the tips is tested on dyes, pigments and biomolecules and enhancement factors higher than 105 are observed. TERS mapping with a spatial resolution of 5 nm is demonstrated.

Download Full-text

Fabrication of highly uniform nanoprobe via the automated process for tip-enhanced Raman spectroscopy

Nanophotonics ◽

10.1515/nanoph-2020-0210 ◽

2020 ◽

Vol 9 (9) ◽

pp. 2989-2996

Author(s):

Dong Hyeon Kim ◽

Chanwoo Lee ◽

Byeong Geun Jeong ◽

Sung Hyuk Kim ◽

Mun Seok Jeong

Keyword(s):

Raman Spectroscopy ◽

Human Error ◽

Acidic Solution ◽

High Spatial Resolution ◽

Electrochemical Etching ◽

Radius Of Curvature ◽

Enhanced Raman Scattering ◽

Tip Enhanced Raman Spectroscopy ◽

Highly Uniform ◽

Etching System

AbstractIn a tip-enhanced Raman spectroscopy (TERS) system, using a sharp nanotip that comprises a noble metal is critical to attaining high spatial resolution and highly enhanced Raman scattering. A strongly acidic solution is typically used to fabricate gold nanotips in a quick and reliable manner. However, using an acidic solution could corrode the etching system, thereby posing hazardous problems. Therefore, both the corrosion of the etching system and human error induced by the conventional method considerably decrease the quality and reproducibility of the tip. In this study, we significantly increased the reproducibility of tip fabrication by automating the electrochemical etching system. In addition, we optimized the etching conditions for an etchant that comprised a KCl solution to which ethanol was added to overcome the limitations of the acidic etchant. The automated etching system significantly increases the yield rate of tip-fabrication reproducibility from 65 to 95%. The standard deviation of the radius of curvature decreased to 7.3 nm with an average radius of curvature of 30 nm. Accordingly, the automated electrochemical etching system might improve the efficiency of TERS.

Download Full-text

Coral-like plasmonic probes for tip-enhanced Raman spectroscopy

Nanoscale ◽

10.1039/d0nr05107a ◽

2020 ◽

Vol 12 (48) ◽

pp. 24376-24384

Author(s):

Angela Capaccio ◽

Antonio Sasso ◽

Oreste Tarallo ◽

Giulia Rusciano

Keyword(s):

Raman Spectroscopy ◽

Spatial Resolution ◽

Single Molecule ◽

Chemical Information ◽

Single Molecule Level ◽

Tip Enhanced Raman Spectroscopy ◽

System Interfaces

Tip-enhanced Raman spectroscopy is a powerful tool for the analysis of system interfaces, enabling access to chemical information with nanometric spatial resolution and sensitivity up to the single molecule level.

Download Full-text