Protonated nitrogen (N2H+) was first
reported as an unidentified triplet line at 93.174 MHz by
in 1974, though various traits pointed to a nitrogen species. On the basis of
quantum chemical calculations,
Green et al.
proposed that the line was likely due to protonated N2. Confirmation of
the species was report in 1975 by
Thaddeus and Turner.
The deuterated form, N2D+, was observed in 1977 by
Snyder et al.
The species has also been in a number of extragalactic sources by
Mauersberger and Henkel and is used for
probing traits of interstellar clouds.
Protonated N2 (also known as
diazenylium) is a linear molecule. Neutral molecules
such as N2 attract cations such as protons. The energy gained when a
proton attaches to a neutral molecules is called the proton affinity. For N2, it is