Rotational spectroscopy of isotopic oxirane, c-C2H4O

We studied the rotational spectrum of oxirane in a sample of natural isotopic composition in selected regions between 158 GHz and 1093 GHz. Investigations of the isotopologs with one 13C or one 18O were the primary focus in order to facilitate searches for them in space. We also examined the main isotopic species mainly to look into the performance of Watson’s A and S reductions both in an oblate and in a prolate representation. Even though oxirane is a rather asymmetric oblate rotor, the A reduction in the IIIl representation did not yield a satisfactory fit, as was observed frequently earlier for other molecules. The other three combinations yielded satisfactory fits of similar quality among each other; the A reduction in the Ir representation required two parameters less than both S reduction fits. [Display omitted] •Rotational spectra of three oxirane isotopologs in natural abundance up to 1.1 THz.•Watson’s A and S reductions tested for main species in Ir and IIIl.•Data for species with one 13C or 18O will help to search for them in space.