Photon counting Raman spectroscopy: a benchmarking study vs surface plasmon enhancement.

Area of Science:

• Spectroscopy
• Photonics
• Analytical Chemistry

Background:

• Raman spectroscopy is a powerful technique for molecular analysis.
• Conventional Raman spectroscopy often suffers from low sensitivity and fluorescence interference.
• Surface-enhanced Raman spectroscopy (SERS) improves sensitivity but requires specific substrates.

Purpose of the Study:

• To demonstrate a single-photon counting Raman spectroscope.
• To benchmark its performance against conventional and SERS.
• To explore its capabilities in time-resolved measurements.

Main Methods:

• Utilized a single-photon counting detector with a common optical setup.
• Employed solutions of Rhodamine 6G for benchmarking.
• Implemented immobilized silver nanoparticles for SERS comparison.
• Performed time-gated and time-correlated single-photon counting.

Main Results:

• Single-photon counting Raman spectroscopy achieved up to an eight-order-of-magnitude increase in detection sensitivity.
• Sensitivity was comparable to surface-enhanced Raman spectroscopy.
• Sub-nanosecond resolution was obtained for time-resolved measurements.
• Demonstrated isolation of Raman scattering from fluorescence signals.

Conclusions:

• Single-photon counting significantly enhances Raman spectroscopy sensitivity and offers time-resolving capabilities.
• This method provides valuable insights into transient sample responses.
• It enables effective discrimination between Raman signals and fluorescence, improving analytical accuracy.