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Studies of extreme-ultraviolet emission from Rydberg series of H/sub 2/ by electron impact

Journal Article · · Phys. Rev. A; (United States)
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Electron excitation cross sections have been measured for the following two Rydberg series of H/sub 2/: /sup 1/..sigma../sub u//sup +/ 1ssigmanpsigma (B, B', and B'', states with principal quantum numbers n = 2, 3, and 4, respectively) and /sup 1/Pi/sub u/ 1ssigmanp..pi.. (C, D, and D' states with principal quantum numbers n = 2, 3, and 4, respectively) over the energy range from threshold to 350 eV. The cross sections for these six states account for all (>99%) of the vacuum-ultraviolet emission (78--170 nm) of the singlet states of H/sub 2/. The estimated total direct-excitation cross sections for these six states at 100 eV in decreasing value are (4.02 +- 0.60) x 10/sup -17/ cm/sup 2/ for B /sup 1/..sigma../sub u//sup +/ (3.86 +- 0.60) x 10/sup -17/ cm/sup 2/ for C /sup 1/Pi/sub u/, (0.76 +- 0.11) x 10/sup -17/ cm/sup 2/ for D /sup 1/Pi/sub u/, (0.76 +- 0.11) x 10/sup -17/ cm/sup 2/ for B' /sup 1/..sigma../sub u//sup +/, (0.30 +- 0.06) x 10/sup -17/ cm/sup 2/ for D' /sup 1/Pi/sub u/, and (0.23 +- 0.05) x 10/sup -17/ cm/sup 2/ for B'' /sup 1/..sigma../sub u//sup +/ and, additionally, (0.43 +- 0.10) x 10/sup -17/ cm/sup 2/ for E,F /sup 1/..sigma../sub g//sup +/ which populates the B /sup 1/..sigma../sub u//sup +/ state through radiative cascade transitions. We estimate the predissociation (autoionization is weak) and emission yields of the vibrational levels of the D, D', and B'' states whose band systems exhibit strong ''breaking off in emission'' for wavelengths below 85 nm.

Research Organization:
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
OSTI ID:
6858075
Journal Information:
Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 29:2; ISSN PLRAA
Country of Publication:
United States
Language:
English

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Related Subjects

640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATMOSPHERES
COLLISIONS
CROSS SECTIONS
DISSOCIATION
ELECTROMAGNETIC RADIATION
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
EMISSION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
EXTREME ULTRAVIOLET RADIATION
HYDROGEN
LYMAN LINES
MOLECULE COLLISIONS
NONMETALS
PHOTON EMISSION
PLANETARY ATMOSPHERES
RADIATIONS
RYDBERG STATES
ULTRAVIOLET RADIATION