Ultrafast Vibrational Energy Transfer in Catalytic Monolayers at Solid-Liquid Interfaces.

Area of Science:

• Surface science
• Catalysis
• Spectroscopy

Background:

• Rhenium-carbonyl complexes are vital CO2-reduction catalysts.
• Understanding molecular interactions on semiconductor surfaces is key for catalyst design.
• Indium-tin-oxide (ITO) is a widely used semiconductor material.

Purpose of the Study:

• To investigate ultrafast vibrational dynamics of rhenium-carbonyl catalysts on ITO.
• To elucidate intermolecular energy transfer mechanisms between adsorbed molecules.
• To determine intermolecular distances based on energy transfer rates.

Main Methods:

• Utilized ultrafast two-dimensional attenuated total reflection infrared (2D ATR IR) spectroscopy.
• Employed isotope-labeled (13C) carbonyl ligands for spectroscopic differentiation.
• Analyzed temporal evolution of cross-peaks for vibrational energy transfer.

Main Results:

• Observed ultrafast vibrational energy transfer between adsorbed molecules.
• Measured time constants of 70 ps (downhill) and 90 ps (uphill) for energy transfer.
• Estimated intermolecular distances of approximately 4-5 Å.

Conclusions:

• Vibrational energy transfer is significantly slower than intramolecular dynamics.
• The estimated intermolecular distance suggests close packing of catalyst molecules.
• This study provides insights into intermolecular coupling on surfaces and explains prior observations.