ABSOLUTE ELECTRON EXCITATION CROSS SECTIONS OF HELIUM
Journal Article
·
· Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D
The absolute apparent electron excitation functions of helium were measured for the 3/sup 1/S, 4/sup 1/S, 5/sup 1/S, 6/sup 1/S, 3/sup 1/P, 4/sup 1/ P, 3/sup 1/D, 4/sup 1/D, 5/sup 1/D, 6/sup 1/D, 3/sup 3/S, 4/sup 3/S, 5/sup 3/S, 3 /sup 3/P, 3/sup 3/D, 4/sup 3/D, 5/sup 3/D, and 6/sup 3/D states at pressures sufficiently low so that the effects of radiation imprisonnaent and collisional excitation transfer can be neglected. The data were corrected for polarization of the radiation and cascading from the upper excited states, and the true excitation functions obtained. The peak values and shape of these excitation functions are compared with results of other laboratories. Generally good agreement is found with previous works where the collisional excitation transfer was properly reduced and allowance made for the cascading effect. The experimental cross sections show satisfactory agreement with the theoretical values calculated by the Born approximation for the /sup 1/S and /sup 1/P states at high electron energies, but are about four times larger than the theoretical values for /sup 1/D states. For the triplet series, the experimental cross sections exceed the calculated values by factors of ten to one hundred or more. It is concluded that the population of the triplet states is produced mainly by processes other than direct excitation. (auth)
- Research Organization:
- Univ. of Oklahoma, Norman
- NSA Number:
- NSA-18-020752
- OSTI ID:
- 4011153
- Journal Information:
- Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 134; ISSN PHRVA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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