<sup>15</sup>N<sup>+</sup> + CD<sub>4</sub> and O<sup>+</sup> + <sup>13</sup>CO<sub>2</sub> State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres
The dissociative photoionization of N2 and O2 by synchrotron radiation in coincidence with threshold photoelectrons is used to produce state-selected N+ and O+ atomic ions to study their reactivity. A pure selection of their ground state, N+(3P) and O+(4S), or excited states, N+(1D), O+(2D), and O+(2P), is obtained by the choice of the photon energy and by further discrimination of atomic ions produced