Electronic states of Ar/sup +//sub 2/, Kr/sup +//sub 2/, Xe/sup +//sub 2/. I. Potential curves with and without spin--orbit coupling
The low-lying states of Ar/sup +//sub 2/, Kr/sup +//sub 2/, and Xe/sup +//sub 2/ have been investigated using the POL CI method. Spin--orbit coupling has been included with a simple atoms-in-molecule approach. The calculated dissociation energies for the ground I (1/2)/sub u/ states of Ar/sup +//sub 2/ and Kr/sup +//sub 2/ are in good agreement (10% error) with experiment, while the agreement is slightly worse (20% error) for Xe/sup +//sub 2/. The well depth decreases from 1.19 eV in Ar/sup +//sub 2/ to 0.79 eV in Xe/sup +//sub 2/ mainly because of spin--orbit effects. As expected, the calculated bond distances increase from Ar/sup +//sub 2/ to Xe/sup +//sub 2/ as the atoms increase in size. The first excited state, I (3/2)/sub g/, possesses a small well (0.12 eV) at larger distances (3--4 A) in all the rare gas dimer ions. The higher excited states arising from the lowest asymptote are more repulsive. There are three dipole-allowed transitions from the ground state. The I (1/2)/sub u/..-->..I (3/2)/sub g/ transition, which occurs in the near infrared, is very weak in accordance with propensity rules based on changes in ..cap omega... The I (1/2)/sub u/..-->..I (1/2)/sub g/ transition occurs between 700--800 nm and grows dramatically in intensity from Ar/sup +//sub 2/ to Xe/sup +//sub 2/ because of spin--orbit effects. The predicted increase in intensity is in excellent agreement with experiment. Finally, the I (1/2)/sub u/..-->..II (1/2)/sub g/ transition is very strong with the intensity decreasing slightly for the heavier rare gas dimer ions. Although the calculated wavelengths for the peak absorption are too long by 20--30 nm, the size and shape of the calculated absorption bands should be in good agreement with experiment. Finally, a comparison is made between the ab initio SCF potentials for the /sup 1/..sigma../sup +//sub g/ state of Ar/sub 2/, Kr/sub 2/, and Xe/sub 2/ with the potentials predicted by the electron gas model.
- Research Organization:
- Theoretical Division, Los Alamos Scientific Laboratory, University of California, Los Alamos, New Mexico 87545
- OSTI ID:
- 5299672
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 68:2
- Country of Publication:
- United States
- Language:
- English
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