Near-Threshold and Resonance Effects in Rotationally Inelastic Scattering of D2O with Normal-H2
Astrid Bergeat1, Alexandre Faure2, Laurent Wiesenfeld3
1Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France.
Molecules (Basel, Switzerland)
|November 11, 2022
Summary
This study details the rotationally inelastic scattering of heavy water (D2O) with hydrogen (H2) using crossed-molecular beam experiments and theoretical calculations. Results show excellent agreement between theory and experiment, particularly in the near-threshold collision energy regime.
Area of Science:
- Chemical Physics
- Molecular Dynamics
- Quantum Scattering
Background:
- Understanding molecular collisions is crucial for chemical kinetics and reaction dynamics.
- The near-threshold regime of scattering is sensitive to long-range interactions and resonance phenomena.
- Heavy water (D2O) and normal hydrogen (H2) collisions provide insights into isotopic effects in molecular interactions.
Purpose of the Study:
- To experimentally and theoretically investigate the rotationally inelastic scattering of D2O with H2.
- To determine state-to-state excitation cross-sections in the low-energy collision regime.
- To compare experimental findings with quantum scattering calculations and analyze isotopic effects.
Main Methods:
- Crossed-molecular beam experiments were conducted in the 10-100 cm^-1 collision energy range.
- Resonance-enhanced multiphoton ionization (REMPI) was used to probe rotational levels of D2O.
- Quantum close-coupling scattering calculations were performed using an accurate D2O-H2 interaction potential.
Main Results:
- Experimental and theoretical cross-sections showed excellent agreement (within 7% relative difference).
- The near-threshold rise and resonance structures in the cross-sections were accurately reproduced.
- The study discussed isotopic effects by comparing D2O-H2 and H2O-H2 scattering.
Conclusions:
- The study validates the accuracy of the theoretical model for D2O-H2 collisions.
- Resonances play a significant role in the near-threshold scattering dynamics.
- The findings contribute to understanding isotopic influences on molecular scattering processes.
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