The torsion-rotation spectrum of D2O2

High-resolution Fourier transform and sub-millimetre torsion-rotation spectra of D2O2 have been recorded between 20 and 1200 cm-1. Spectra involving the torsional levels (n,t) = (0,1), (0,3), (1,1), (1,3), (2,1), (2,3), and (3,1) have been observed and assigned.The Hamiltonian that has been used with success in the analysis of H2O2 surprisingly proved to be inadequate for D2O2 because the smaller torsional spacings give rise to some near resonances with |D Ka| = 3 that do not occur in H2O2. Once this extra interaction was included the spectra have been fitted fairly well. The observed levels are too far below the cis-torsional barrier for the staggering of the even and odd K values to be observed.