Doubly excited states of molecular hydrogen by scattered electron-ion coincidence measurements*
1 Department of Physics, Rikkyo
2 Department of Physics, Toho University, Miyama, Funabashi, 274-8510 Chiba, Japan
Received in final form: 10 February 2014
Published online: 23 April 2014
Electron energy-loss spectroscopy and electron-ion coincidence techniques were used to determine the total generalized oscillator strength distribution (GOSD) of molecular hydrogen (H2) under 200 eV incident electron energy at a scattering angle of 6 degree. Ionic GOSDs were obtained for each formed ion at each energy-loss value and were determined by scattered electron-ion coincidence measurements. The total and partial ionic GOSDs of H2 were compared with the OOSDs from the experimental results of both photon and fast-electron impacts. We observed auto-ionization induced by excitation to the optically forbidden Q1 1Σ+g(1) state near 28 eV. Additionally, the non-ionic GOSD, defined as the difference between the total GOSD and the total ionic GOSD, was determined. From the non-ionic GOSD, neutral dissociation from excitation to the forbidden Q1 1Σ+g(1) state near 28 eV and the Q2 series near 35 eV were identified.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2014