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Published on: November 9, 2019
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Reactivity and internal dynamics in the Criegee intermediate CH2OOCO2 system: A rotational study.
Carlos Cabezas1, Adam M Daly2, Yasuki Endo3
1Instituto de Física Fundamental (IFF-CSIC), Group of Molecular Astrophysics, C/Serrano 121, 28006 Madrid, Spain.
Summary
The reaction between the simplest Criegee intermediate (CH2OO) and carbon dioxide (CO2) was studied. Researchers observed a weakly bound complex, indicating limited reactivity between these atmospheric molecules.
Area of Science:
- Atmospheric Chemistry
- Physical Chemistry
- Spectroscopy
Background:
- Criegee intermediates (CIs) are key species in atmospheric chemistry, influencing aerosol formation and air quality.
- The reaction of CIs with carbon dioxide (CO2), a major greenhouse gas, is crucial for understanding atmospheric processes.
Purpose of the Study:
- To investigate the reaction system between the simplest Criegee intermediate, CH2OO, and CO2.
- To characterize the weakly bound CH2OO-CO2 complex and its properties.
Main Methods:
- Fourier transform microwave spectroscopy was employed to study the reaction system.
- A two-state torsion-rotation Hamiltonian was utilized to analyze the rotational spectrum.
- Ab initio calculations were performed for theoretical validation.
Main Results:
- The CH2OO-CO2 weakly bound complex was successfully identified in the rotational spectrum.
- Inversion doublets, indicative of tunneling motion, were observed, providing insights into the complex's structure.
- Rotational and centrifugal distortion constants for both tunneling states were derived, and the torsional energy difference was determined to be 23.9687 MHz.
Conclusions:
- The study confirms the formation of a weakly bound CH2OO-CO2 complex.
- The observed limited reactivity and non-observation of a cycloaddition product align with theoretical predictions.
- This research contributes to a better understanding of the atmospheric fate and impact of Criegee intermediates.
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