H/sub 2/ fluorescence spectrum from 1200 to 1700 A by electron impact: Laboratory study and application to Jovian aurora

Journal Article · Mon Mar 15 04:00:00 EST 1982 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/183757· OSTI ID:5289417

Yung, Y L; Gladstone, G R; Chang, K M; Ajello, J M; Srivastava, S K

A combined experimental study of the fluorescence spectrum of H/sub 2/ at wavelengths of 1200--1700 A by electron impact and its application to modeling the Jovian aurora have been carried out. Our laboratory data suggest that at 100 eV the relative cross sections for direct excitation of Ly..cap alpha.., Lyman bands (B/sup 1/..sigma../sup +//sub u/-X/sup 1/..sigma../sup +//sub g/), and Werner bands (C/sup 1/..pi../sub u/-X/sup 1/..sigma../sup +//sub g/) are 1, 2.3 +- 0.6, and 2.6 +- 0.5, respectively, in conflict with Stone and Zipf's (1972) results for the Werner bands. Cascade from E, F/sup 1/..sigma../sup +//sub g/ states contributes an additional 31% to the B/sup 1/..sigma../sup +//sub u/ state population. It is shown that the most likely fate for the metastable H(2/sup 2/S) atoms produced in the Jovian aurora is collisional quenching to H(2/sup 2/P), and this could add as much as 60% to the predicted Ly..cap alpha.. emission. On the basis of detailed atmospheric and radiative transfer modeling, we conclude that the recent IUE and Voyager observations are consistent with precipitation of electrons with energy in the range of 1--30 keV or other energetic particles that penetrate to number densities of 4 x 10/sup 10/--5 x 10/sup 13/ cm/sup -3/ or column densities of 5 x 10/sup 17/--2 x 10/sup 20/ cm/sup -2/ in the atmosphere. The globally averaged energy flux and production of hydrogen atoms are 0.5--2 ergs cm/sup -2/ and 1--4 x 10/sup 10/ atoms cm/sup -2/ s/sup -1/, respectively.

• Research Organization: Division of Geological and Planetary Sciences, California Institute of Technology
• OSTI ID: 5289417
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 254:2; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
640304 -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
ATMOSPHERES
COLLISIONS
CROSS SECTIONS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
EMISSION SPECTROSCOPY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
FLUORESCENCE SPECTROSCOPY
HYDROGEN
JUPITER PLANET
LYMAN LINES
MOLECULE COLLISIONS
NONMETALS
PLANETARY ATMOSPHERES
PLANETS
SPECTROSCOPY