Millimeter-Wave Spectrum of Hydrogen Peroxide

Some 50 rotational transitions of HOOH in the ground vibrational state have been measured in the millimeter-wave region from 60 to 300 kMc/sec. Analysis of these transitions provides a complete set of values of the rotational constants and the accurate value of 342 885.0 ± 2.0 Mc/sec for the doublet splitting of the ground-state vibrational levels by internal barrier tunneling. The rotational constants in the Hamiltonian for the semirigid-rotor model with an internal axis of rotation are (in megacycles per second): ν01,201,2 = 276 208.0 ± 2.0, ν03,403,4 = 275 912.7 ± 2.0, β01,201,2 = 25 662.1 ± 2.0, β03,403,4 = 25 673.7 ± 2.0, γ01,201,2 = 542.96 ± 0.5, γ03,403,4 = 476.64 ± 0.5. The dihedral angle of the OH bonds is found to be 120°1′ ± 15′ for the lower level and 116°7′ ± 15′ for the upper level of the ground-state doublet. Some 30 millimeter-wave rotational transitions for DOOD were also measured, but analysis of them is not yet complete.