Metastable Peaks in the Mass Spectra of N2 and NO

Abstract

Metastable ions dissociating by unimolecular transitions have been observed in the mass spectra of N₂ and NO at $\text{(M\hspace{0.17em}/\hspace{0.17em}q)*\hspace{0.17em}=\hspace{0.17em}7.00}$ and $\text{(M\hspace{0.17em}/\hspace{0.17em}q)*\hspace{0.17em}=\hspace{0.17em}8.53}$ , respectively. In N₂ the transition of N₂⁺ to N⁺ is shown to occur from a state with an A.P. of 24.9 ± 0.3 eV. The kinetic‐energy release is 0.55 ± 0.10 eV; hence the dissociation is to the limit ${\mathrm{N}}^{+}{(}^3\mathrm{P)\hspace{0.17em}+\hspace{0.17em}}\mathrm{N}{(}^4{S}_0)$ at 24.30 eV. In NO the dissociation is to the limit ${\mathrm{O}}^{+}{(}^4{S}_0\mathrm{)\hspace{0.17em}+\hspace{0.17em}}\mathrm{N}{(}^4{S}_0)$ at 20.101 eV. The observed A.P. and kinetic‐energy release are 20.2 ± 0.2 and 0.04 ± 0.02 eV, respectively. Possible mechanisms of metastable dissociation by tunneling or predissociation are suggested.