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Vibrational Autodetachment from Anionic Nitroalkane Chains: From Molecular Signatures to Thermionic Emission
Christopher L Adams1, Klavs Hansen2,3, J Mathias Weber1
1JILA and Department of Chemistry , University of Colorado , Boulder , Colorado 80309-0440 , United States.
The Journal of Physical Chemistry. A
|September 19, 2019
Summary
Electron autodetachment from nitroalkane anions reveals kinetic energy distributions. Unlike nitromethane, these distributions lack distinct vibrational features, suggesting thermionic emission governs the process.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Molecular Dynamics
Background:
- Electron autodetachment is a key process in understanding anion dynamics.
- Nitroalkanes are important model systems for studying electron interactions.
- Previous studies on nitromethane showed distinct vibrational features in electron autodetachment.
Purpose of the Study:
- To investigate the kinetic energy distributions of electrons released from nitroethane, 1-nitropropane, and 1-nitrobutane anions.
- To compare the electron autodetachment dynamics of these longer-chain nitroalkanes with that of nitromethane.
- To explore the influence of molecular structure on electron detachment mechanisms.
Main Methods:
- Velocity map electron imaging was employed to measure kinetic energy distributions.
- Laser excitation targeted specific CH stretching modes in the anions.
- Analysis focused on the shape and features of the kinetic energy distributions.
Main Results:
- Kinetic energy distributions for nitroethane, 1-nitropropane, and 1-nitrobutane anions showed minimal distinct vibrational features.
- The observed distributions were well-described by a thermionic emission model.
- The electron capture cross section of the neutral molecule influenced the distribution shape.
- A classical description was applicable for electron kinetic energies above approximately 20 meV.
- Quantum effects were found to suppress the attachment cross section at lower electron energies.
Conclusions:
- The electron autodetachment dynamics of longer-chain nitroalkanes differ significantly from nitromethane.
- Thermionic emission is a dominant mechanism for electron release in these systems.
- Both classical and quantum mechanical descriptions are necessary to fully understand electron attachment processes across different energy regimes.
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