Mutual Neutralization of ${\mathrm{NO}}^{+}$ with ${\mathrm{O}}^{-}$

We have studied the mutual neutralization reaction of vibronically cold ${\mathrm{NO}}^{+}$ with ${\mathrm{O}}^{-}$ at a collision energy of $\approx 0.1\mathrm{eV}$ and under single-collision conditions. The reaction is completely dominated by production of three ground-state atomic fragments. We employ product-momentum analysis in the framework of a simple model, which assumes the anion acts only as an electron donor and the product neutral molecule acts as a free rotor, to conclude that the process occurs in a two-step mechanism via an intermediate Rydberg state of NO which subsequently fragments.

Figure 1

Kinetic energy release distributions of the $\mathrm{N}+\mathrm{O}+\mathrm{O}$ products at two different storage time intervals. The full lines results from fits assuming a constant rotational distribution ($T_{\mathrm{rot}}=1500\mathrm{K}$) and a vibrational distribution described by $T_{\mathrm{vib}}=3000\mathrm{K}$ (a), and $T_{\mathrm{vib}}=22\mathrm{K}$ (b). The vibrational state positions and populations are represented by the vertical bars.

Figure 2

(a) Breakup geometries in the Dalitz coordinates. The blue and two red arrows at each point correspond to the velocity vectors of the nitrogen and oxygen atoms, respectively. Each dotted line corresponds to the fraction of the total energy that each particle takes, with the vertical blue line corresponding to that of the nitrogen atom. Since the two oxygen atoms cannot be distinguished, the plot is symmetric with respect to the N line. (b) Experimental Dalitz distribution for all MN events after 1 s of storage. (c) Simulated Dalitz distribution using the free rotor model [32] with $\mathrm{\Delta }E=0.95\mathrm{eV}$, corresponding to the $E{}^2{\mathrm{\Sigma }}^{+}$ state (d) with $\mathrm{\Delta }E=50\mathrm{meV}$, corresponding to the $D{}^2{\mathrm{\Sigma }}^{+}$ state.

Figure 3

Selected potential energy curves of ${\mathrm{NO}}^{+}$ and NO. Adapted from [18, 33, 34, 35].