Vibrational Temperature of O2+ and N2+ Drifting at Elevated EN in Helium

Abstract

The vibrational temperature, $T_v$, of ${\mathrm{N}}_2^{+}$ and ${\mathrm{O}}_2^{+}$ ions drifting in a helium buffer has been determined for the first time quantitatively as a function of $\frac{E}{N}$. For both ions $T_v$ reaches ∼ 3000 K at $\frac{E}{N}\simeq 150\times {10}^{17}$ V·${\mathrm{cm}}^2$. This result resolves various previously inexplicable aspects of the behavior of ion-neutral reactions as a function of energy.