Collisional depopulation of He(n /sup 1/P) (4< or =n< or =13) in thermal collisions with He(1 /sup 1/S)
Total collisional depopulation rates for He(n /sup 1/P) (4< or =n< or =13) in thermal collisions with He(1 /sup 1/S) have been measured using the transient-decay method. Related loss cross sections increase in proportion to n/sup 4/ in the limited range 4< or =n< or =6, reach a maximum of 2600 +- 600 A/sup 2/ at n = 10, and decrease approximately in proportion to n/sup -2.5/ for 11< or =n< or =13. The measurements were found to be inconsistent with a strong ''selection rule,'' ..delta..L = 2, for the He(n /sup 1/P)-He collisions. A model in which ..delta..L for the collision is largely unrestricted provides a satisfactory interpretation of the observations, in agreement with recent l-mixing studies of atomic Rydberg levels. The experimental cross sections compare favorably with values calculated using an approximate scaling formula for collisional l mixing and, for n>10, with predictions based on a simple perturbation treatment in the weak-collision approximation.
- Research Organization:
- Research Institute of Physics, S-10405 Stockholm 50, Sweden and Physics Department, Royal Institute of Technology, S-10044 Stockholm 70, Sweden
- OSTI ID:
- 5267901
- Journal Information:
- Phys. Rev. A; (United States), Vol. 28:6
- Country of Publication:
- United States
- Language:
- English
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HELIUM
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640304* - Atomic
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640302 - Atomic
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