ELECTRON EXCITATION CROSS SECTIONS FOR THE 2s~2 2p~2 ~3P→2s~2 2p~2 ~1D TRANSITION IN O~(2+)

摘要

Absolute experimental excitation cross sections are reported for the combined 2s~2 2p~2 ~3P_(0,1,2)→2s~2 2p~2 ~1D_2 spin- and symmetry-forbidden transitions in O~(2+). These excitations correspond to the optical emission wavelengths λ5009.0 (J = 2 → 2) and 14960.9 (J = 2 → 1). Use is made in the measurements of the electron energy-loss method with merged electron and ion beams. Data are reported for the center-of-mass collision energy range of 2.48 eV (threshold) to 5.35 eV (or 2.2 x threshold). One finds agreement between experiment and some of the predictions of resonances in a recent 26 state R-matrix calculation. In particular, experiment confirms the presence of strong, narrow resonances near 2.7 and 4.2 eV, detectable with an experimental electron-beam energy spread of only 0.10 eV (FWHM). Resonance enhancement predicted at 3.1 eV is absent in the experiment.