Photoionisation study of Xe.CF4 and Kr.CF4 van-der-Waals molecules
V A Alekseev1, G A Garcia2, R Kevorkyants1
1St. Petersburg State University, 7/9 Universitetskaya Nab., St. Petersburg 199034, Russia.
The Journal of Chemical Physics
|May 16, 2016
Summary
Photoionization studies of Xenon-Carbon tetrafluoride (Xe·CF4) and Krypton-Carbon tetrafluoride (Kr·CF4) van-der-Waals complexes reveal insights into their ionic stability. Calculations indicate ions prefer a vertex geometry, differing from neutral complexes.
Area of Science:
- Physical Chemistry
- Atomic and Molecular Physics
- Chemical Physics
Background:
- Van der Waals complexes offer insights into intermolecular forces.
- Understanding the ionization dynamics of noble gas-CF4 complexes is crucial for molecular physics.
Purpose of the Study:
- Investigate the photoionization of Xe·CF4 and Kr·CF4 van der Waals complexes.
- Determine the stability and structural properties of the resulting Rg·CF4+ ions.
- Compare experimental findings with ab initio calculations.
Main Methods:
- Production of van der Waals complexes in a supersonic expansion.
- Photoionization studies using synchrotron radiation.
- Photoelectron-photoion coincidence (PECOI) spectroscopy.
- Complementary ab initio quantum chemical calculations.
Main Results:
- The ionization potential of CF4 is higher than that of Xe and Kr atoms.
- Rg·CF4+ ion ground states correlate with Rg+ ((2)P3/2) + CF4.
- Ion signals appear ~0.2 eV below the atomic Rg ionization potential.
- Calculations show vertical transitions terminate ~0.05 eV below the Rg+ + CF4 dissociation limit.
- Neutral complexes favor face geometry, while ions favor vertex geometry.
- No Xe·CF4+ signal observed above the Xe ionization threshold, indicating instability.
Conclusions:
- Rg·CF4+ ions are likely unstable above the first dissociation limit.
- Structural rearrangements occur upon ionization, with ions adopting a vertex geometry.
- Experimental and computational methods provide consistent insights into complex ion behavior.
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