THE RQ2-BRANCH OF HOOH AT 1.05 THZ

The lower frequency (r)Q2-branch of the torsional split rotational spe ctrum of HOOH has been recorded for the first time near 1.05 THz with Doppler limited resolution employing a Backward Wave Oscillator as the radiation source. The position of the Q-branch lines can be predicted very closely from a set of effective rotational constants derived ind ividually for the two torsionally split levels. The symmetry of the mo lecule, and the height of the potential barrier against internal rotat ion, are the two main reasons for the clear separation between the rot ational and torsional contributions to the spectrum of HOOH as well as the analogous molecule HSSH.