Fully absorptive 3D IR spectroscopy using a dual mid-infrared pulse shaper

Area of Science:

• Physical Chemistry
• Spectroscopy
• Chemical Physics

Background:

• Two-dimensional Infrared (2D IR) spectroscopy is a powerful technique for studying molecular dynamics.
• Limitations in existing 2D IR methods necessitate advancements for more comprehensive spectral analysis.
• Vibrational spectroscopy provides insights into molecular structure and interactions.

Purpose of the Study:

• To implement and demonstrate a novel three-dimensional Infrared (3D IR) spectroscopy technique.
• To enhance spectral resolution and information content compared to traditional 2D IR methods.
• To enable simultaneous collection of rephasing and non-rephasing signals for absorptive spectra.

Main Methods:

• Modification of a two-beam 2D IR spectrometer by incorporating a second mid-IR pump beam.
• Utilizing independent pulse shapers for each pump beam, allowing programmable time- or frequency-domain collection.
• Employing phase cycling to isolate fifth-order signals from third-order signals.

Main Results:

• Successful implementation of 3D IR spectroscopy, automatically acquiring absorptive spectra.
• Demonstration on tungsten hexacarbonyl (W(CO)6) and dicarbonylacetylacetonato rhodium (I).
• Extraction of molecular eigenstates up to the third excited state for the studied compounds.

Conclusions:

• The developed 3D IR spectroscopy method offers significant control over experiments.
• Pulse shaping enables mixed time- and frequency-domain experiments and fast data acquisition.
• This technique provides a more straightforward and powerful approach to vibrational spectroscopy.