Emission cross section and vibrational branching ratios of the N2O+ (Ã 2Σ+ −X̃ 2Π) band produced by He* (2 3S) impact on N2O

Photoemission cross sections of Penning ionization have been measured at 150 meV for collision of He*(2 3S) with N2O by using the crossed-beam method and observing fluorescence in the 335–415 nm region. The emission cross section of the N2O+ (A2Σ+ −X 2Π) system obtained is (7.7 ± 2.1) × 10−20 m2. The band strengths of the 110 and 311 bands relative to the 000 band, s(110)/s(000) and s(311)/s(000, are evaluated to be 0.105 ± 0.007 and 0.045 ± 0.003, respectively. The s(110)/s(000) ratio indicates non-Franck-Condon behavior, which is attributable to the 7δ→eδ shape resonant ionization near 20 eV.