Attenuated total reflectance spectroscopy with chirped-pulse upconversion.

Area of Science:

• Spectroscopy
• Physical Chemistry
• Chemical Dynamics

Background:

• Attenuated total reflectance (ATR) infrared spectroscopy is a powerful technique for analyzing liquid samples.
• Traditional methods can be limited by speed and spectral range.
• Developing faster, broader-range spectroscopic methods is crucial for studying dynamic processes.

Purpose of the Study:

• To apply a chirped-pulse upconversion technique to attenuated total reflectance (ATR) infrared spectroscopy.
• To achieve rapid, single-shot absorption spectra measurements of liquids.
• To investigate the dynamics of solvent exchange processes.

Main Methods:

• Utilized a chirped-pulse upconversion technique with an ATR diamond prism.
• Generated an extremely broadband infrared pulse.
• Employed four-wave mixing in krypton gas to convert the reflected infrared pulse to the visible spectrum.
• Measured absorption spectra using a visible spectrometer.

Main Results:

• Successfully measured absorption spectra of liquids from 200 to 5500 cm(-1) on a single-shot basis.
• Observed the dynamics of solvent exchange between water and acetone.
• Determined that the solvent exchange process was completed within approximately 10 milliseconds.

Conclusions:

• The chirped-pulse upconversion technique is effective for ATR infrared spectroscopy.
• This method allows for rapid, time-resolved measurements of liquid dynamics.
• The technique provides clear vibrational spectral contrast for distinguishing between different solvents.