Microwave spectra of the ground and excited vibrational states of isotopic specees of nitroethylene

Rotational Spectra of nitroethylene, four deuterium and six C-13 species have been measured and analysed in the frequency range ftorn 8 to 26 GHz, Rotational transitions in the ground state, in progressions or excited states of the NO2 torsional mode nu(18), in the in-plane skeletal bending mode nu(13), and in doubly excited states nu(13)nu(13)+nu(18)nu(18) could be assigned for nitroethylene and its deuterated species. The spectra of the C-13 isotopic species were observed in natural abundance and their assignments have partly been checked by microwave - microwave (mw - mw) double resonance. All the spectra in each of the different vibrationally excited states were found to acceptably obey a rigid rotor pattern with centrifugal distortion, corresponding to a high barrier for the NO2 internal rotation. Rotational constants and inertia defects all show the same qualitative dependence on the internal state. The ground state rotational constants of all isotopic species have been used to determine a refined molecular structure.