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Delayed ionization and fragmentation en route to thermionic emission: statistics and dynamics.
1School of Physics and Engineering Physics, Göteborg University, Göteborg, SE-41296 Sweden. eleanor.campbell@fy.chalmers.se
Annual Review of Physical Chemistry
|October 14, 2000
Summary
Thermionic emission, a slow decay process, involves energy-rich molecules and clusters releasing electrons over microseconds. Future research should explore experimental signatures and theoretical aspects of this delayed ionization.
Area of Science:
- Physical Chemistry
- Chemical Physics
- Materials Science
Background:
- Thermionic emission is a decay mechanism for excited molecules and clusters.
- This process can occur over extended timescales (microseconds).
- It is relevant for large molecules, metallic clusters, and fullerenes.
Purpose of the Study:
- To review the current understanding of thermionic emission as a long-time decay mode.
- To identify knowledge gaps and necessary future research directions.
- To highlight experimental and theoretical challenges.
Main Methods:
- Review of existing experimental data and theoretical studies.
- Discussion of potential experimental signatures.
- Analysis of theoretical indications of delayed ionization.
Main Results:
- Thermionic emission can be a slow (microseconds) decay process.
- Delayed ionization may not follow purely statistical behavior.
- Electron emission competes with fragmentation and radiative cooling.
Conclusions:
- Coupling between electronic and nuclear modes can delay ionization.
- Long time-delayed ionization is observable, preceding full energy partitioning.
- Further experimental and theoretical work is crucial for a complete understanding.