Evidence for Predissociation ofN2intoN(D2)+N(D2)from New High-Resolution Vacuum-Ultraviolet Emission Bands

The use of a low-pressure discharge lamp has permitted us to discover many new emission bands of ${\mathrm{N}}_2$ at short wavelengths, in the vacuum ultraviolet. Strong evidence of predissociation is afforded by the sharp breaking off in the rotational structure of some bands corresponding to transitions originating from an electronic state different in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}_2^{}{}_{}{}^{}$ and ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}_2^{}{}_{}{}^{}$. The respective limits give, directly, an improved upper limit for the dissociation into $\mathrm{N}\left({}_{}{}^2{}_{}{}^{}D\right)+\mathrm{N}\left({}_{}{}^2{}_{}{}^{}D\right)$, furnishing clear-cut evidence for setting definitely the dissociation energies of ${\mathrm{N}}_2$.