The rotational spectrum of cis-cis HOONO has been studied over a broad range of frequencies,13-840 GHz,using pulsed beam Fourier-transform microwave spectroscopy and room-temperature flow cell submillimeter spectroscopy.The rotational spectrum of the deuterated isotopomer,cis-cis DOONO,has been studied over a subset of this range,84-640 GHz.Improved spectroscopic constants have been determined for HOONO,and the DOONO spectrum is analyzed for the first time.Weak-field Stark effect measurements in the region of 84-110 GHz have been employed to determine the molecular dipole moments of cis-cis HOONO [mu_a= 0.542(8) D,mu_b =0.918(15) D,mu=1.07(2) D] and DOONO [mu_a=0.517(9) D,mu_b=0.930(15) D,mu=1.06(2) D].The quadrupole coupling tensor in the principal inertial axis system for the ~(14)N nucleus has been determined to be X_(aa)=1.4907(25) MHz,x_(bb)=-4.5990(59) MHz,x_(ab)=3.17(147) MHz,and X_(cc)=3.1082(59) MHz.Coordinates of the H atom in the center-of-mass frame have been determined with use of the Kraitchman equations,|a_H| =0.516 A and |b_H|=1.171 A.The inertial defects of HOONO and DOONO are consistent with a planar equilibrium structure with significant out-of-plane H atom torsional motion.Comparisons of the present results are made to ab initio calculations.
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