Vibrational Excitation and Compound States in NO

The cross section for elastic scattering by electron impact on NO shows resonances in the energy range 0-2 eV. These resonances, with a spacing of about 0.16 eV (${\ensuremath{\omega}}_{e}=0.17$ eV), are associated with vibrational levels of ${\mathrm{NO}}^{\ensuremath{-}}$, and there is a near-coincidence in energy between the 4th vibrational state of NO and the 6th vibrational state of ${\mathrm{NO}}^{\ensuremath{-}}$. The width of these resonances increases monotonically from 0.02 to 0.10 eV as the vibrational quantum number of ${\mathrm{NO}}^{\ensuremath{-}}$ goes from 1 to 6. The energy dependence of the vibrational cross sections exhibits peaks at the positions of these resonances, and the magnitude of these peaks is measured. The vibrational states of ${\mathrm{NO}}^{\ensuremath{-}}$ can decay by the emission of an electron into various vibrational levels of NO. The branching ratio for a few of these decays is measured. A potential energy diagram of ${\mathrm{NO}}^{\ensuremath{-}}$ is drawn, using the experimental evidence.