Muon-nuclear quadrupolar level crossing resonance in solid nitrogen Evidence for [N₂MuN₂]⁺ complex formation?

Abstract

The recent interpretation that the μ⁺ SR signal in crystalline nitrogen at 37 K arises from N₂μ⁺(also written as N₂μ⁺) is examined in the light of ab initio calculations using Hartree-Fock, second-order Møller-Plesset, quadratic configuration interaction and density functional methods. It is concluded that the intrinsic nitrogen quadrupole interaction (2·26 MHz) is too large by more than a factor of two to be assigned to the species N₂Mu⁺. Calculations are extended to the linear complex [N₂MuN₂]⁺, which is shown to be more stable and gives a quadrupole interaction closer to the experimental value.