MUON-NUCLEAR QUADRUPOLAR LEVEL-CROSSING RESONANCE IN SOLID NITROGEN -EVIDENCE FOR [N(2)MUN(2)](-FORMATION() COMPLEX)

The recent interpretation that the mu(+) SR signal in crystalline nitr ogen at 37 K arises from N(2)Mu(+) (also written as N-2 mu(+)) is exam ined in the light of ab initio calculations using Hartree-Fock, second -order Moller-Plesset, quadratic configuration interaction and density functional methods. It is concluded that the intrinsic nitrogen quadr upole interaction (2.26 MHz) is too large by more than a factor of two to be assigned to the species N(2)Mu(+). Calculations are extended to the linear complex [N(2)MuN(2)](+), which is shown to be more stable and gives a quadrupole interaction closer to the experimental value.