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Please use this identifier to cite or link to this item: http://hdl.handle.net/2014/39252

Title: The electron excited ultraviolet spectrum of HD : cross sections and transition probabilities
Authors: Ajello, Joseph
Palle, Prahlad Vatti
Abgrall, Herve´
Roueff, Evelyne
Bhardwaj, Anil
Gustin, Jacques
Keywords: molecular data
Issue Date: Aug-2005
Publisher: American Astronomical Society
Citation: The Astrophysical Journal Supplement Series, 159;314-330.
Abstract: We have analyzed the high-resolution ultraviolet (UV) emission spectrum of molecular deuterium hydride (HD) excited by electron impact at 100 eV under optically thin, single-scattering experimental conditions. The high-resolution spectrum (FWHM=160 mÅ) spans the wavelength range from 900 to 1650 Å and contains the two Rydberg series of HD: 1 +u1s , np (B, B , B , n=2, 3, 4) X 1 +g and 1 +u1s , np (C, D, D , D , n=2, 3, 4, 5) X 1 +g. A model spectrum of HD, based on newly calculated transition probabilities and line positions including rovibrational coupling for the strongest band systems, B 1 +u X 1 +g, B 1 +u X 1 +g, C 1 u X 1 +g, and D 1 u X 1 +g, is in excellent agreement with observed intensities. The cross sections for direct excitation at 100 eV of the B 1 +u, B 1 +u, C 1 u, and D 1 u states were derived from a model analysis of the experimental fluorescence spectrum to the ground state. The absolute cross section values for excitation to the B 1 +u, B 1 +u, C 1 u, and D 1 u states were found to be (2.57±0.26)×10-17, (0.22±0.06)×10-17, (2.54±0.25)×10-17, and (0.17±0.04)×10-17 cm2, respectively. We have also determined the dissociative excitation cross sections at 100 eV for the emission of Ly at 1216 Å and Ly at 1025 Å lines, which are (7.98±1.12)×10-18 and (0.40±0.10)×10-18 cm2, respectively. The summed excitation function of the closely spaced pair of lines, H Ly and D Ly , resulting from dissociative excitation of HD, has been measured from the threshold to 800 eV and is analytically modeled with a semiempirical relation. The model cross sections are in good agreement with the corrected Ly cross sections of Möhlmann et al. up to 2 keV. Based on measurements of H, D (2s) production cross section values by Möhlmann et al., the H, D (n=2) cross section is estimated to be 1.6×10-17 cm2 at 100 eV.
URI: http://hdl.handle.net/2014/39252
Appears in Collections:JPL TRS 1992+

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