Photon-Particle Coincidence Measurement of Charge-Transfer Excitation of theN2+First Negative 3914-Å Band by Protons

Abstract

The cross section for charge-transfer excitation of the ${N_2}^{+}$ first negative 3914-Å band by protons (5-65 keV) has been measured using a photon-particle coincidence technique. The target ${\mathrm{N}}_2$ is collisionally excited to the ${{\mathrm{N}}_2}^{+} \left(B {}_{}{}^2{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}\right)$ state and emits a 3914-Å photon in the (0,0) transition. This photon is detected in coincidence with the scattered particle, a proton or hydrogen atom, allowing separation of the two reactions which contribute to 3914-Å emission. The cross section for charge-transfer excitation indicates that charge transfer is the dominant contributor to 3914-Å excitation at energies below 10 keV, and that ionization with excitation becomes increasingly important with increasing energy. The by-product measurements, which include the cross section for charge transfer, the total cross section for 3914-Å emission, and the lifetime of the ${{\mathrm{N}}_2}^{+} \left(B {}_{}{}^2{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}\right)$ state, agree well with those of other workers.