The high-resolution spectrum of O-2-N2O, the first for a complex conta
ining more than one unpaired electron, has been studied in the region
of the nu(3) N2O monomer vibrational band using a molecular beam diode
laser absorption spectrometer. The spectrum has been completely analy
zed using a newly developed effective Hamiltonian. The rotational cons
tants are accurately determined for both ground and excited vibrationa
l states. The equilibrium structure of the complex is planar, with a s
eparation between the centers of the mass of two monomers of 3.423 Ang
strom. The structural angles have been experimentally determined as: e
ither theta(O2) = 58 degrees and theta(N2O) = 77 degrees, or theta(O2)
= 122 degrees and theta(N3O) = 100 degrees. The large amplitude motio
n of the monomers leads to the complex having an effective out-of-plan
e root mean square angle of phi = phi(1)-phi(2) approximate to 23 degr
ees. In addition, an interpretation of the structure of the complex is
given in terms of an intermolecular potential using a model described
by Muenter. (C) 1997 American Institute of Physics.