The electronic emission spectrum of ionized nitrous oxide, N ₂ O ₊ : Ã ₂ Σ ₊ —X ₂ Π

The emission spectrum of the transition $\tilde{A}^{2}\Sigma ^{+}-\tilde{X}^{2}\Pi $ between the two lowest states of the ion of N$_{2}$O have been photographed under high resolution and analysed in both of the two isotopes N$_{2}{}^{16}$O$^{+}$ and N$_{2}{}^{18}$O$^{+}$. The principal vibrational structure yields the stretching fundamentals in both states (table 11), from which complete sets of quadratic valence stretching force constants are obtained, albeit uncorrected for anharmonicities (table 14). The excited state $\tilde{A}^{2}\Sigma $ is more tightly bound than the neutral N$_{2}$O in its ground state. Sequences in the bending vibration show the effects of moderate Renner-Teller vibronic coupling in the orbitally degenerate $^{2}\Pi $-state ($\epsilon $ = -0.19); and together with a few weaker bands of different polarization involving $\Delta $v$_{2}$ = $\pm $ 1 observed presumably through Herzberg-Teller vibronic coupling, these transitions make possible a complete analysis of the Renner coupling in v$_{2}^{\prime \prime}$ = 1 (table 10) and hence yield the bending frequencies and force constants. This analysis provides one of the best tests so far of the Renner-Pople-Hougen theory of these couplings. Rotational analysis gives zero-point moments of inertia I$_{0}$ from which r$_{0}$- structures are calculated for both states (table 13). Finally, the force constants and bond distances of the ion are compared with those of the neutral molecule, and the states of the ion correlated with those of possible dissociation products (table 16).