Production of stable and autoionizing O2− and NO− ions in CsO2 and CsNO collisions

Abstract

Abstract We present absolute total cross sections for electron and ion production in CsNO and CsO 2 collisions. The laboratory energy of the cesium atoms varied between 30 and 3000 eV. The branching ratio between electron and ion production in these systems provides a direct measure for the amount of molecular anions which are produced in stable or autoionizing vibrational states. The absolute magnitude of the observed cross sections shows that the ionization process is due to a curve crossing between the potentials of the covalent and ionic ground states. The experiment shows that CsNO collisions predominantly lead to production of NO − ions in the vibrational ground state. For both CsNO and CsO 2 collisions the distribution over vibrational states of the molecular anions is a function of the collision energy. The experimental results are discussed on the basis of several models.