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Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
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Photoelectron wave function in photoionization: plane wave or Coulomb wave?
Samer Gozem1, Anastasia O Gunina1, Takatoshi Ichino2
1Department of Chemistry, University of Southern California , Los Angeles, California 90089-0482, United States.
The Journal of Physical Chemistry Letters
|October 29, 2015
Summary
Accurate photoionization cross sections require precise wave functions. This study shows that using Coulomb waves with adjusted charges improves calculations for molecules, enhancing accuracy.
Area of Science:
- Atomic and Molecular Physics
- Quantum Chemistry
- Spectroscopy
Background:
- Calculating absolute total cross sections for photoionization and photodetachment necessitates accurate wave functions for the photoelectron and the system's initial/final states.
- Dyson orbitals effectively condense the essential information from the initial and final states of the system.
Purpose of the Study:
- To evaluate approximate treatments of the photoelectron wave function, specifically plane and Coulomb waves.
- To compare computed and experimental photoionization and photodetachment spectra to determine the most accurate models.
- To establish reliable methods for calculating molecular photoionization cross sections.
Main Methods:
- Employing correlated Dyson orbitals to represent initial and final electronic states.
- Testing plane wave approximations for photoelectron wave functions in anionic systems.
- Utilizing Coulomb wave approximations with varying effective charges for photoionization of neutral atoms and molecules.
- Comparing computational results with experimental photoionization and photodetachment spectra.
Main Results:
- Plane wave treatment accurately describes photodetachment spectra for anions.
- Coulomb wave treatment is essential for photoionization of atoms/small molecules due to core charge interaction.
- For larger molecules, a Coulomb wave with a partial charge (<1) yields the best agreement with experimental data.
- The effective charge at the Dyson orbital centroid is smaller than the total cation charge in polyatomic systems.
Conclusions:
- The choice of photoelectron wave function approximation significantly impacts the accuracy of calculated cross sections.
- A modified central potential model, adjusting the charge based on the Dyson orbital centroid, can accurately compute molecular photoionization cross sections.
- This approach accounts for the nonspherical charge distribution of the ionized core, improving theoretical predictions.
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