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Laboratory studies of uv emissions of H_2 by electron impact. The Werner- and Lyman-band systems

Ajello, J. M. and Srivastava, S. K. and Yung, Yuk L. (1982) Laboratory studies of uv emissions of H_2 by electron impact. The Werner- and Lyman-band systems. Physical Review A, 25 (5). pp. 2485-2498. ISSN 1050-2947. http://resolver.caltech.edu/CaltechAUTHORS:20140910-153452680

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Abstract

We report a laboratory measurement of absolute emission cross sections of both the Lyman bands (B^1Σ_u^+→X^1Σ_g^+) and Werner bands (C^1Π_u→X^1Π_g^+) of H_2 by electron impact over the energy range from threshold to 400 eV with the same optical system. We find the emission cross section for the B^1Σ_u^+→X^1Σ_g^+ transition at 100 eV to be (3.55±0.8) × 10^(−17) cm^2 (2.7 × 10^(−17) cm^2, direct excitation, 0.85 × 10^(−17) cm^2, cascading) and the emission cross section for the C^1Π_u→X^1Σ_g^+ transition at 100 eV to be (3.1±0.6) × 10^(−17) cm^2 (cascading is estimated to be not present). The cross-section ratio Qc/Qb for direct excitation is 1.21±0.30 at 300 eV in excellent agreement with published values for this ratio from theoretical calculations and experimental data of the optical oscillator strengths. We measure the cross section for cascading to the B state to be 24±10% of the total emission cross section both at 100 and 300 eV. We show that cascading increases to 51±20% of the total cross section of the B state at 20 eV. The vibrational population distribution of the B state is found to be a function of electron-impact energy as the importance of cascading relative to direct excitation changes with electron-impact energy.


Item Type:Article
Related URLs:
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https://journals.aps.org/pra/abstract/10.1103/PhysRevA.25.2485PublisherArticle
http://dx.doi.org/10.1103/PhysRevA.25.2485DOIArticle
Alternate Title:Laboratory studies of uv emissions of H2 by electron impact. The Werner- and Lyman-band systems
Additional Information:© 1982 The American Physical Society. Received 1 October 1981. Published in the issue dated May 1982. This work was supported by the Planetary Atmospheres, Astronomy/Relativity and Laser Kinetics Programs of NASA. It represents one phase of work sponsored by NASA under Contract No. NAS7-100 to the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109.
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NASANAS7-100
Record Number:CaltechAUTHORS:20140910-153452680
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140910-153452680
Official Citation:Laboratory studies of uv emissions of H2 by electron impact. The Werner- and Lyman-band systems J. M. Ajello, S. K. Srivastava, and Yuk L. Yung Phys. Rev. A 25, 2485-2498 (1982) – Published 1 May 1982
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49564
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:10 Sep 2014 23:16
Last Modified:10 Sep 2014 23:16

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