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06:53
Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Dissociative electron attachment resonances in ammonia: a velocity slice imaging based study
N Bhargava Ram1, E Krishnakumar
1LaserLab and Physical Chemistry, Vrije Universiteit, Amsterdam 1081 HV, The Netherlands. nbhargavram@gmail.com
The Journal of Chemical Physics
|May 8, 2012
Summary
Negative ion resonance states of ammonia were studied. These states produce fragment anions, H(-) and NH(2)(-), with distinct fragmentation pathways and geometric rearrangements.
Area of Science:
- Physical Chemistry
- Atomic and Molecular Physics
- Quantum Chemistry
Background:
- Negative ion resonance states are transient, unstable species formed by electron capture.
- Ammonia (NH3) is a fundamental molecule with important chemical and physical properties.
- Understanding fragmentation dynamics provides insights into molecular structure and bonding.
Purpose of the Study:
- To investigate the dissociation dynamics of negative ion resonance states in ammonia.
- To determine the symmetry of these resonance states using experimental data.
- To explore geometric rearrangements occurring in excited ammonia negative ions.
Main Methods:
- Electron scattering experiments utilizing the velocity slice imaging technique.
- Measurement of fragment anion (H(-) and NH(2)(-)) angular and kinetic energy distributions.
- Analysis of scattering patterns to deduce resonance symmetries.
Main Results:
- Two distinct resonance states of ammonia negative ions were accessed at 5.5 eV and 10.5 eV.
- Fragment anions H(-) and NH(2)(-) were produced through different fragmentation channels.
- Angular distributions indicated geometric rearrangement of the NH(3)(-) ion, differing from neutral ammonia's equilibrium geometry.
- Forward-backward asymmetry was observed in fragment ion scattering at 10.5 eV.
- Resonance symmetries were determined as A(1) at 5.5 eV and E at 10.5 eV within C(3v) geometry.
Conclusions:
- The study elucidates the fragmentation mechanisms of ammonia negative ion resonances.
- Experimental evidence supports geometric rearrangement in excited NH(3)(-) states.
- The determined symmetries (A(1) and E) contribute to a deeper understanding of ammonia's electronic structure.
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