High-Resolution Electron-Impact Study of the Far-Ultraviolet Emission Spectrum of Molecular Hydrogen

Total transition probability and spontaneous radiative dissociation of B, C, B′ and D states of molecular hydrogen

“…In diffuse and translucent interstellar clouds, this emission takes place after radiative absorption and controls the transition between atomic and molecular gas (Stephens & Dalgarno 1972;Black & Dalgarno 1977;Abgrall et al 1992) whereas electronic collisional excitation is the source of excitation in the atmospheres of outer planets (Liu et al 1998). We had also calculated the continuum fluorescence spectrum up to J = 10 and compared successfully our theoretical results with experiments performed at the Jet Propulsion Laboratory (Liu et al 1995;Abgrall et al 1997). The kinetic energy released in the emergent hydrogen atoms is a heating mechanism in the considered environment (Stephens & Dalgarno 1973).…”

THE HIGH-RESOLUTION EXTREME-ULTRAVIOLET SPECTRUM OF N 2 BY ELECTRON IMPACT

“…The experimental apparatus has been described in detail in previous papers (Liu et al 1995;Ajello et al 1995aAjello et al , 1995bAjello et al , 2002Ajello et al , 2011a, and we will only describe the setup in a general way here. We use an Acton VM-523-SG 3.0 m UV spectrometer at JPL, allowing for what is probably the highest-resolution single-scattering electron-impact emission instrument in use in the United States.…”

“…The energy resolution of the electron beam is 1 eV. The absolute energy of the electron beam is calibrated by measuring the appearance potential of H Lyα following dissociative excitation of H 2 at 14.68 eV (Ajello & James 1991;Ajello et al 1995aAjello et al , 1995bLiu et al 1995). We have performed wavelength scans with the N 2 target molecules effusing into the collision chamber from a capillary array with alternative background gas pressures of 4.4 × 10 −6 and 2.0 × 10 −4 torr.…”

ELECTRON IMPACT DISSOCIATION X 1 Σ + g → b 3 Σ u + AND EXCITATIONS Ki1, Jung2 2013ApJS8000View full textAdd to dashboardCite

“…Detailed theoretical calculations have provided the mean energies and yields for the ionization, electronic excitation, dissociation, and vibrational excitation produced by energetic electrons traversing a gas mixture containing molecular hydrogen (Dalgarno et al 1999). The Jet Propulsion Laboratory group of Ajello has contributed a quite useful and considerable amount of data for molecular hydrogen from their systematic studies of electron-impact UV emissions (Ajello & Shemansky 1993;Liu et al 1995Liu et al , 1998Liu et al , 2003James et al 1998;Jonin et al 2000). For molecular hydrogen, the three electronic excitation transitions:…”