Transient stimulated Raman scattering spectroscopy and imaging

Area of Science:

• Chemical Imaging
• Spectroscopy
• Quantum Coherence

Background:

• Stimulated Raman scattering (SRS) is a key quantitative chemical imaging technique.
• Current SRS methods suffer from spectral broadening, limiting resolution and sensitivity.
• Existing SRS techniques face trade-offs between spectral resolution, range, and acquisition speed.

Purpose of the Study:

• To introduce transient stimulated Raman scattering (T-SRS) as a novel time-domain strategy.
• To overcome fundamental limitations of frequency-domain SRS imaging.
• To achieve natural linewidth spectral resolution and enhanced sensitivity in SRS.

Main Methods:

• Utilizing quantum coherence manipulation and femtosecond pulse-pair sequences.
• Encoding vibrational oscillations in the stimulated Raman loss (SRL) signal.
• Acquiring time-domain SRL signals and performing Fourier transforms for spectral analysis.

Main Results:

• T-SRS achieves natural-linewidth-limit spectral line shapes and laser-bandwidth-determined spectral range.
• Sensitivity is boosted to the sub-millimolar (sub-mM) level for typical Raman modes using ~150-fs laser pulses.
• Demonstrated hyperspectral SRS imaging of live-cell metabolism and high-density multiplexed imaging with high spectral resolution.

Conclusions:

• T-SRS provides a breakthrough in SRS imaging by bypassing traditional conjugations between sensitivity, spectral resolution, range, and speed.
• The technique enables high-fidelity spectral data acquisition, crucial for detailed chemical analysis.
• T-SRS holds significant potential for diverse advanced Raman imaging applications, including live-cell analysis.