Single-Shot Sub-microsecond Mid-infrared Spectroscopy on Protein Reactions with Quantum Cascade Laser Frequency Combs

Area of Science:

• Spectroscopy
• Biophysics
• Chemical Kinetics

Background:

• Analyzing irreversible protein reactions demands techniques for time-resolved infrared spectra.
• Existing methods may lack the speed, resolution, or sensitivity for capturing rapid molecular events.

Purpose of the Study:

• To develop and demonstrate a novel spectrometer for single-shot, time-resolved infrared spectral analysis.
• To enable the study of fast enzymatic reactions with high temporal and spectral resolution.

Main Methods:

• Utilized dual-frequency-comb spectroscopy with mid-infrared quantum cascade lasers.
• Generated frequency combs to record absorption spectra in the 55 cm^-1 fingerprint region.
• Achieved sub-microsecond time resolution and high spectral resolution (0.3 cm^-1).

Main Results:

• Successfully demonstrated simultaneous spectral and transient recording of photoactivated bacteriorhodopsin.
• Showcased that a single excitation event is sufficient to extract spectral and kinetic data of photocycle intermediates.
• Achieved low noise levels in the μOD range.

Conclusions:

• The developed spectrometer provides a powerful tool for noninvasive analysis of enzymatic conversions.
• Offers high time resolution, broad spectral coverage, and minimal sample consumption for kinetic studies.
• Paves the way for advanced investigations into fast biological processes.