Nuclear spin conversion in NH{sub 3}
Journal Article
·
· Physical Review. A
- Laboratoire de Physique des Lasers, Atomes et Molecules, Centre d'Etudes et de Recherches Lasers et Applications (CERLA), Universite Lille 1, 59655 Villeneuve d'Ascq Cedex (France)
The nuclear spin conversion (NSC) rate for a gas sample of NH{sub 3} is calculated in the framework of the quantum relaxation model. It is based on the knowledge of the vibration-inversion levels of the lowest vibrational states, the relaxation rates, and the intramolecular magnetic interactions. The magnitudes of the spin-spin and spin-rotation interaction terms have been obtained with the help of ab initio calculations. The value of the NSC at 296 K for a pressure of 1 Torr is 3.23x10{sup -6} s{sup -1} for {sup 14}NH{sub 3} and 9.15x10{sup -6} s{sup -1} for {sup 15}NH{sub 3}. A linear dependence of the NSC rates on the pressure is valid up to 1 atm for {sup 14}NH{sub 3} and up to 30 Torr for {sup 15}NH{sub 3}, where quasidegenerate ortho/para pairs are present in the excited {nu}{sub 2}=1 state.
- OSTI ID:
- 21316393
- Journal Information:
- Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 80; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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