Magic cluster ion distributions: (NO)3+ (N2O)n and (NO)3+ (CO2)n

Supersonic jet expansions of mixtures of nitric oxide with either nitrous oxide or carbon dioxide have been investigated over a wide range of relative concentrations. Mixed molecular cluster ions of the form (NO)_m⁺ (N₂O)_n and (NO)_m⁺ (CO₂)_n are detected following non-resonant two-photon ionization. Over a wide range of intermediate concentrations, the cluster ion distributions (NO)₃⁺ (N₂O)_n and (NO)₃⁺ (CO₂)_n with n30 are significantly more intense than clusters containing other numbers of nitric oxide molecules. The extra abundance of these species is attributed to their especially stable structures and several possible forms are discussed. An intriguing possibility involves a stable cyclic nitric oxide trimer (or ion) when combined with nitrous oxide or carbon dioxide clusters.