Electronic Resonant Stimulated Raman Scattering Micro-Spectroscopy.

Area of Science:

• Spectroscopy
• Microscopy
• Biophysics

Background:

• Electronic pre-resonance stimulated Raman scattering (epr-SRS) microscopy enables super-multiplex imaging.
• Under electronic resonance, background signals from pump-probe processes obscure desired vibrational information.
• Vibrational signatures of chromophores are critical for molecular identification and analysis.

Purpose of the Study:

• To demonstrate electronic resonant stimulated Raman scattering (er-SRS) microspectroscopy and imaging.
• To suppress electronic background noise for improved vibrational signal retrieval.
• To achieve ultrasensitive biological imaging and single-molecule Raman detection.

Main Methods:

• Development of er-SRS microspectroscopy and imaging techniques.
• Suppression of electronic background signals.
• Analysis of vibrational band shape changes under electronic resonance.
• Determination of resonant Raman cross sections via power-dependence studies and excitation profile calculations.

Main Results:

• Observed distinct changes in vibrational band shapes (Lorentzian, dispersive, inverted Lorentzian) with approaching electronic resonance.
• Successfully retrieved vibrational peaks after suppressing electronic background.
• Estimated resonance Raman cross sections up to 10^-23 cm^2 in er-SRS.
• Achieved a ~100-fold increase in Raman cross section compared to epr-SRS.

Conclusions:

• er-SRS microspectroscopy effectively suppresses electronic background, enabling clear vibrational signal detection.
• The enhanced Raman cross section in er-SRS significantly advances sensitivity.
• These findings pave the way for single-molecule Raman detection and ultrasensitive biological imaging applications.