Electron ionization dynamics ofN2andO2molecules: Velocity-map imaging

Abstract

This paper reports a crossed-beam velocity-map imaging study into the electron ionization dynamics of jet-cooled ${\mathrm{N}}_{2}$ and ${\mathrm{O}}_{2}$ molecules at electron collision energies from 35 to 100 eV. The use of velocity-map imaging detection provides insight into the detailed ionization dynamics through the dimension of the product ion kinetic energy associated with impulsive dissociation. In particular, ``mesoscopic'' cross sections corresponding to ionization from manifolds of energetically close states converging to the same dissociation asymptote are reported for a number of single-ionization channels. In addition, a range of double-ionization cross sections have been characterized, including those yielding ${{X}_{2}}^{2+}$ dications. These are found to be in excellent agreement with other cross sections determined in coincidence measurements. This agreement supports a meaningful and accurate determination of the single-ionization channels.