Abstract
A tip-enhanced Raman spectroscopy (TERS) system based on an atomic force microscope (AFM) and radially polarized laser beam was developed. A TERS probe with plasmon resonance wavelength matching the excitation wavelength was prepared with the help of dark-field micrographs. The intrinsic photoluminescence (PL) from the silver (Ag)-coated TERS probe induced by localized surface plasmon resonance contains information about the near-field enhanced electromagnetic field intensity of the probe. Therefore, we used the intensity change of Ag PL to evaluate the stability of the Ag-coated probe during TERS experiments. Tracking the Ag PL of the TERS probe was helpful to detect probe damage and hotspot alignment. Our setup was successfully used for the TERS imaging of single-walled carbon nanotubes, which demonstrated that the Ag PL of the TERS probe is a good criterion to assist in the hotspot alignment procedure required for TERS experiments. This method lowers the risk of contamination and damage of the precious TERS probe, making it worthwhile for wide adoption in TERS experiments.
Highlights
Tip-enhanced Raman spectroscopy (TERS) is a near-field enhanced Raman spectroscopy imaging technique that can obtain high-resolution topographical image and in-situ nanoscale chemical fingerprint information simultaneously [1]
The plasmon enhancement capability of the tip-enhanced Raman spectroscopy (TERS) probe gradually decrease over time, especially after the hotspot is generated at the apex of the probe
Because of the near-field thermal effect [36] and the force applied to the apex of the probe, the oxidation and wear rate of the Ag film on the probe apex will accelerate after hotspot generation
Summary
Tip-enhanced Raman spectroscopy (TERS) is a near-field enhanced Raman spectroscopy imaging technique that can obtain high-resolution topographical image and in-situ nanoscale chemical fingerprint information simultaneously [1]. Scanning the laser beam has the advantage that no tip movement is needed, protecting the probe from damage during the hotspot alignment This method increases the complexity of the system because an additional auxiliary component such as a galvanometer scanner is required [20,21,22]. The PL of Ag or Au nanostructures is widely observed in SERS spectra as a broad and continuous background because of the strong LSPR enhanced electromagnetic field [29] This wide range of metal PL background existing in raw SERS spectra receives little attention and is usually removed by precise baseline correction [30] to extract the Raman signals of interest. To accelerate the initial alignment of the apex of the TERS probe relative to the laser focal spot, we optimize the optical path in our TERS configuration
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
