Electron impact ionization cross section of metastable N2(A Σ+u)

Abstract
The nondissociative electron impact ionization cross section of the metastable N2(A 3Σ+u) state is measured from threshold to 240 eV. Rising from an appearance potential of 10.1±0.6 eV, the cross section peaks at about 40 eV with a value of (1.14±0.36)×10−16 cm2. These values are extracted from the apparent ionization cross section of an N2 beam composed of ∼50% N2(A 3Σ+u) and ∼50% N2(X 1Σ+g). This mixed state beam is formed by charge transfer neutralization of a 1 keV N+2 beam with NO. The N2(A 3Σ+u) cross section is normalized by measuring it relative to the ionization of a ground state N2 beam formed by charge transfer neutralization of N+2 with N2.