A reexamination of important N2cross sections by electron impact with application to the dayglow: The Lyman-Birge-Hopfield Band System and N I (119.99 nm)

摘要: The far ultraviolet emission spectrum (120 to 210 nm) of electron-excited N2 has been obtained in a crossed-beam laboratory experiment. cross section the Lyman-Birge-Hopfield (LBH) band system (a¹Πg → X¹Σg+) remeasured using experimental techniques we have previously developed for this metastable transition. improved data set a¹Πg state allows determination excitation, emission, and predissociation from threshold 200 eV use planetary atmosphere models dayglow aurora. An analytic fit accurate estimates arbitrarily high excitation energy. close agreement both energy dependence absolute values between measurements, presented here, published electron scattering results shows cascade is small (<5%). total estimated be 6.22 ± 1.37×10−18 cm² at 100 eV. absence bands υ′ ≥ 7 suggests yield unity. function each vibrational level found same shape within 5%. In low-energy region, e < 20 eV, differences lead significant departure relative sections Franck-Condon distribution. Thus LBH population distribution or aurora affected by flux; show that atmospheric need include effect. N I (119.99 also 3.48 0.77×10−18 on basis comparison with Lyman α dissociative H2.