Non-Franck-Condon electron-impact dissociative-excitation cross sections of molecular hydrogen producingH(1s)+H(2l)through

Itamar Borges

¹

,

Ginette Jalbert

²

,

Carlos Eduardo Bielschowsky

³

Electron-impact dissociative excitation cross sections for singlet states of molecular hydrogen

“…More recently, thermally averaged DE cross sections for the singlet ungerade continua have been estimated by Liu et al [13] using a modified Born approximation with input from experiment for excitation functions, for incident electron energies from threshold to 1000 eV. Overall, the previous calculations [8][9][10][11][12][13] are in broad agreement at high incident energies, however they differ significantly from threshold to intermediate energies with discrepancies of up to a factor of three for some transitions.…”

“…Cross sections for the production of H(1s) and H(2s) atoms via excitation of the B ′ 1 Σ + u , E, F 1 Σ + g , and e 3 Σ + u states were calculated by Chung et al [8] using the Born-Rudge and Born-Ochkur theories, Mu-Tao et al [9] using the distorted wave approximation, and by Liu and Hagstrom [10] using the Bethe approximation. The first Born approximation has been applied by Borges et al [11] at high impact energies (E i = 100-1000 eV) for DE of the B 1 Σ + u and C 1 Π u states (leading to the production of H(1s) and H(2p) atoms) and the B ′ 1 Σ + u state (producing H(1s) and H(2s)). Additionally, Celib- * Electronic address: liam.scarlett@postgrad.curtin.edu.au erto et al [12] calculated cross sections describing DE to several low lying singlet states and the b 3 Σ + u state using the impact-parameter method for scattering on all vibrational levels of the ground electronic state.…”

“…However, production of such fragments is not limited to the DE process; predissociation, radiative cascades from higher states, and autoionization all contribute to the yield of atomic hydrogen. These processes must be included in theoretical calculations, making accurate comparison with measurements of H(n, ℓ) production difficult [11]. However, lowenergy DE measurements have also been inferred from time-of-flight and electron energy-loss measurements for DE via the repulsive b 3 Σ + u state (producing two H(1s) atoms) [17][18][19].…”

Configuration interaction oscillator strengths of the H2O molecule: Transitions from the ground to the B∼1A1Borges1 2006Chemical PhysicsSelf Cite11000View full textAdd to dashboardCite

“…The inaccuracy of the HF/MR-CI OOS values might stem from the use of the Molpro program, known as optimized for CAS/MR-CI calculations and not for HF/MR-CI ones. This belief comes from previous experience of this author on accurate HF/MR-CI calculations of the hydrogen molecule using another suite of programs (the Caltech suite) [31,32]. Further work on the comparison of computed molecular properties using either SCF or CAS orbitals in MR-CI calculations would be valuable in order to clarify these matters.…”

Electron-Impact Dissociation of Vibrationally-Excited Molecular Hydrogen into Neutral Fragments

“…Furthermore, a proper treatment of dissociation (including excitation-radiative-decay dissociation) requires collision data resolved not only in the electronic levels, but in the initial and final vibrational levels, which vastly increases the computational expense of the calculations. Prior to the CCC estimates of dissociation [6], calculations were limited to low incident energies where only a small number of reaction channels are open [8][9][10], or large energies where the Born approximation may be applied [11]. No attempts were made to produce a dissociation cross section including all reaction channels over a wide range of incident energies.…”