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Photodissociation of CH3I: a full-dimensional (9D) quantum dynamics study
Christian R Evenhuis1, Uwe Manthe
1Theoretische Chemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615 Bielefeld, Germany.
The Journal of Physical Chemistry. A
|February 12, 2011
Summary
This study uses wave packet dynamics to simulate methyl iodide photodissociation. Calculations reveal strong coupling between C-I stretching and bending motions, largely matching experimental results for product distributions.
Area of Science:
- Chemical Physics
- Molecular Dynamics
- Spectroscopy
Background:
- Methyl iodide photodissociation is a key process in atmospheric chemistry and photochemistry.
- Understanding the dynamics of this process provides insights into bond breaking and molecular fragmentation.
Purpose of the Study:
- To investigate the photodissociation of methyl iodide in the A band using advanced computational methods.
- To compare theoretical predictions with experimental data for absorption spectra and product distributions.
Main Methods:
- Full-dimensional (9D) wave packet dynamics calculations.
- Utilizing the multiconfigurational time-dependent Hartree (MCTDH) approach.
- Employing diabatic potential energy surfaces and ab initio calculations for excitation energies.
Main Results:
- The calculated absorption spectrum for parallel excitation closely matches experimental data.
- Strong coupling between C-I stretching and H(3)-C-I bending motions influences dissociation dynamics.
- Computed rotational and vibrational product distributions generally agree with experimental trends, with some discrepancies in methyl fragment excitation.
Conclusions:
- The study validates the use of wave packet dynamics for methyl iodide photodissociation.
- The findings highlight the importance of specific molecular motions in the dissociation pathway.
- Discrepancies suggest potential limitations of the employed diabatic model for certain vibrational modes.
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