Tip-enhanced Raman spectroscopy: near-fields acting on a few molecules

Area of Science:

• Chemical Physics
• Surface Science
• Nanotechnology

Background:

• Surface-enhanced Raman spectroscopy (SERS) provides high sensitivity but lacks spatial resolution.
• Tip-enhanced Raman spectroscopy (TERS) is a powerful variant of SERS, retaining sensitivity while significantly improving spatial resolution.

Purpose of the Study:

• To review the capabilities and advancements in Tip-enhanced Raman spectroscopy (TERS).
• To discuss TERS enhancements, contrasts, and applications in surface science, material science, and biology.
• To present recent developments in ultrahigh vacuum TERS.

Main Methods:

• TERS utilizes a sharp metallic tip to enhance Raman signals, achieving sub-diffraction-limited spatial resolution.
• Correlation of topographic and chemical data through simultaneous imaging.
• Investigation of TERS enhancements, contrasts, and single-molecule detection.

Main Results:

• TERS overcomes SERS drawbacks, offering high sensitivity and spatial resolution beyond the Abbe limit.
• Single-molecule TERS has been achieved with enhancements of 10^6-10^7.
• Demonstration of TERS on nanoscale C(60) islands under ultrahigh vacuum conditions.

Conclusions:

• TERS is a versatile technique enabling detailed chemical and topographical analysis at the nanoscale.
• Advancements in TERS, particularly under UHV, expand its applicability in fundamental research and materials characterization.