Transient two-dimensional IR spectrometer for probing nanosecond temperature-jump kinetics.

Area of Science:

• Physical Chemistry
• Biophysics
• Spectroscopy

Background:

• Studying rapid molecular dynamics requires advanced spectroscopic techniques.
• Nanosecond temperature jumps (T-jumps) are crucial for initiating and observing fast chemical and biophysical processes.
• Existing methods face challenges in synchronizing diverse laser systems and maintaining signal quality.

Purpose of the Study:

• To develop a Fourier transform two-dimensional infrared (2D IR) spectrometer capable of probing processes initiated by nanosecond T-jumps.
• To overcome technical hurdles in synchronizing nanosecond and femtosecond lasers, enhancing signal-to-noise ratio, and managing interferometric measurements in dynamic samples.
• To demonstrate the applicability of this novel technique for studying molecular structure changes.

Main Methods:

• Development of a synchronized laser system using a Ti:sapphire oscillator clock for 2 ns timing accuracy.
• Implementation of a balanced detection scheme with a dual stripe array detector and undersampling to improve signal-to-noise ratio.
• Application of transient dispersed vibrational echo and 2D IR spectroscopy to N-methylacetamide and ubiquitin.

Main Results:

• Successful synchronization of nanosecond T-jump and femtosecond laser systems was achieved.
• Improved signal-to-noise ratio and reduced data acquisition time were demonstrated.
• Spectral responses to temperature elevation and protein structural changes were successfully measured and compared.

Conclusions:

• The developed 2D IR spectrometer effectively probes molecular structure changes induced by nanosecond perturbations.
• This technique opens new avenues for nonlinear spectroscopy in studying ultrafast dynamics.
• The methodology is applicable to various chemical reactions and biophysical processes.