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Influence of formation path on the CH2BrCl2+ dissociation dynamics
1Laboratoire de Chimie-Physique, Matière et Rayonnement (LCPMR), UMR 7614, Université P. et M. Curie, 11 rue P. et M. Curie, F-75231 Paris cedex 05, France. klg@ccr.jussieu.fr
The Journal of Chemical Physics
|September 17, 2005
Summary
Site-specific bond breaking in bromochloromethane (CH2BrCl) is driven by Auger decay, preferentially leading to C-Br bond rupture. This contrasts with C-Cl bond breaking, which shows no selective signature in threshold dication formation.
Area of Science:
- Physical Chemistry
- Atomic and Molecular Physics
- Chemical Physics
Background:
- Inner-shell ionization of molecules like bromochloromethane (CH2BrCl) can lead to site-selective fragmentation.
- Understanding the mechanisms behind this selective bond breaking is crucial for predicting molecular dissociation pathways.
Purpose of the Study:
- To investigate the origin of site-specific bond breaking in CH2BrCl following ionization.
- To analyze the dissociation properties of the CH2BrCl2+ dication formed at threshold.
- To correlate Auger decay processes with selective fragmentation pathways.
Main Methods:
- High-resolution Br 3d and Cl 2p Auger spectroscopy.
- Spin-orbit resolved Br 3d Auger spectra acquisition.
- Threshold electron-pair ion coincidence measurements to study dication dissociation.
Main Results:
- Auger decay preferentially populates specific dication states, initiating site-specific bond breaking.
- Predominant C-Br bond breaking was observed in both threshold and inner-shell ionization studies.
- No evidence of selective C-Cl bond rupture was found for the threshold-formed dication.
Conclusions:
- The Auger decay process itself is the primary driver of site-specific bond breaking in CH2BrCl.
- The C-Br bond is significantly more susceptible to rupture than the C-Cl bond at the dication threshold.
- These findings provide insight into the fundamental mechanisms governing molecular fragmentation after ionization.