Two-dimensional infrared spectroscopy using a fast-scanning interferometer and chirped pulse upconversion at 100 kHz

Area of Science:

• Spectroscopy
• Physical Chemistry
• Biophysics

Background:

• Two-dimensional infrared (2DIR) spectroscopy is a powerful tool for studying molecular dynamics.
• Existing 100-kHz 2DIR spectrometers face limitations in spectral resolution and noise reduction.

Purpose of the Study:

• To develop and demonstrate a novel 100-kHz 2DIR spectrometer with improved spectral resolution.
• To apply the new spectrometer to measure the 2DIR spectrum of carboxyhemoglobin.

Main Methods:

• Utilized a 100-kHz pump-probe spectrometer.
• Employed chirped-pulse upconversion (CPU) for spectrally resolving probe pulses with a CMOS camera.
• Generated the two-pulse pump sequence using a conventional interferometer with a fast-scanning mechanical delay line (2 Hz scanning frequency).

Main Results:

• Achieved a modulation frequency of 3.1 kHz, effectively shifting the signal away from low-frequency noise.
• Demonstrated improved spectral resolution in both pump and probe dimensions compared to existing technologies.
• Successfully measured the 2DIR spectrum of carboxyhemoglobin.

Conclusions:

• The combined use of an interferometer and CPU in a 100-kHz 2DIR spectrometer significantly enhances spectral resolution.
• This advanced spectroscopic technique offers a superior alternative to current methods for molecular dynamics studies.