Knowledge Bank

The microwave spectrum of the $Ar-NO2$ open-shell complex has been measured for the $KA=0$ and 2 states using a pulsed Fourier transform spectrometer between 7 and 18 GHz. We are able to study the interaction of the radical with its closed shell partner, which is expected to be intermediate between chemical and physical bonding. Also, the long range coupling of the electronic spin and orbital angular momenta to the intermolecular motion is important in the chemistry of free radicals. The high resolution offered by microwave spectroscopy has allowed us to probe fine, magnetic hyperfine and electric quadrupole interactions found in this system. The $KA=0$ data has been fitted to a semi-rigid Hamiltonian to determine the molecular parameters for this state, and have been used to derive an effective structure.$ K_{A} = 2$ transitions have also been observed. Full analysis of both these states will be presented, along with the implications the derived parameters have on the electronic and geometric structure of the complex.