Tetranitrogen (N ₄ ), which has been the subject of great theoretical interest, has been prepared from the N ₄ ⁺ cation and positively detected as a gaseous metastable molecule with a lifetime exceeding 1 microsecond in experiments based on neutralization-reionization mass spectrometry. An examination of the geometry of N ₄ ⁺ and the fragmentation pattern of the ¹⁴ N ₂ ¹⁵ N ₂ neutral molecule has revealed that the latter is characterized by an open-chain geometry with two distinct, closely bound N ₂ units joined by a longer weaker bond.

Hydrogen trioxide (HO ₃ ) has long been postulated as a key intermediate in important atmospheric processes but has proved difficult to detect. The molecule was unequivocally detected in experiments based on neutralization-reionization and neutralization-reionization/collisionally activated dissociation mass spectrometry, using protonated ozone (HO ₃ ⁺ ) as the charged precursor. Hydrogen trioxide is a relatively stable species and has a H-O-O-O connectivity and a lifetime exceeding 10 ^–6 seconds at ambient temperature.

The characterization of the non covalent interaction potential, responsible for the intermolecular bond in NO–N₂ and (NO–N₂)⁺ molecular aggregates, has been achieved by coupling the predictions of a semiempirical method with the results of a scattering experiment and ab initio calculations. The potential wells for the most stable configurations of the neutral and ionic state, having approximatively a T shape in both cases, fall in the same intermolecular distance range. In addition, in the ionic state, the charge is completely localized on the NO partner. Important implications on the dynamics of the neutralization process, occurring as a vertical transition from ionic to neutral state, are obtained by exploiting the analytical formulation of the interaction and calculating energy spacings and relevant Franck–Condon factors for both intramolecular and intermolecular vibration modes.