Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

Laboratory studies of uv emission of H/sub 2/ by electron impact. The Werner- and Lyman-band systems

Journal Article · · Phys. Rev. A; (United States)
; ;

We report a laboratory measurement of absolute emission cross sections of both the 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/Pi/sup +//sub g/) of H/sub 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 /sup 1/..sigma../sup +//sub u/..-->..X /sup 1/..sigma../sup +//sub g/ transition at 100 eV to be (3.55 +- 0.8) x 10/sup -17/ cm/sup 2/ (2.7 x 10/sup -17/ cm /sup 2/, direct excitation, 0.85 x 10/sup -17/ cm/sup 2/, cascading) and the emission cross section for the C/sup 1/Pi/sub u/..-->..X /sup 1/..sigma../sup +//sub g/ transition at 100 eV to be (3.1 +- 0.6) x 10/sup -17/ cm/sup 2/ (cascading is estimated to be not present). The cross-section ratio Q/sub A//Q/sub B/ 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.

Research Organization:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
OSTI ID:
5233164
Journal Information:
Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 25:5; ISSN PLRAA
Country of Publication:
United States
Language:
English

Similar Records

Studies of extreme-ultraviolet emission from Rydberg series of H/sub 2/ by electron impact
Journal Article · Tue Jan 31 23:00:00 EST 1984 · Phys. Rev. A; (United States) · OSTI ID:6858075
Electron-impact excitation of the singlet states of N/sub 2/. I. The Birge--Hopfield system (b/sup 1/. pi. /sub u/--X/sup 1/. sigma. /sup +//sub g/)
Journal Article · Tue Jul 15 00:00:00 EDT 1980 · J. Chem. Phys.; (United States) · OSTI ID:5335970
H/sub 2/ fluorescence spectrum from 1200 to 1700 A by electron impact: Laboratory study and application to Jovian aurora
Journal Article · Sun Mar 14 23:00:00 EST 1982 · Astrophys. J., Lett. Ed.; (United States) · OSTI ID:5289417

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
640304 -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
CROSS SECTIONS
ELECTROMAGNETIC RADIATION
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EV RANGE 100-1000
HYDROGEN
LYMAN LINES
MOLECULE COLLISIONS
NONMETALS
RADIATIONS
ULTRAVIOLET RADIATION