The millimeter and sub-millimeter rotational spectrum of triple

Context. A recently published astronomical detection of all three doubly 13C-substituted ethyl cyanides toward Sgr B2(N2) motivated us to investigate triple 13C isotopic species that are expected to be also present in the ISM. Aims. We aim to present an experimental study of the rotational spectrum of triple 13C-substituted ethyl cyanide, 13CH313CH213CN, in the frequency range 150–990 GHz. We want to use the determined spectroscopic parameters for searching for 13CH313CH213CN in ALMA data. The main objective of this work is to provide accurate frequency predictions to search for this molecule in the Galactic center source Sagittarius B2(N) and to facilitate its detection in space. Methods. The laboratory rotational spectrum of 13CH313CH213CN has been recorded with the Lille’s fast DDS solid-state spectrometer between 150 GHz and 990 GHz. Results. More than 4000 rotational transitions were identified in the laboratory. The quantum numbers reach J = 115 and Ka = 39. Watson’s Hamiltonian in the A and S reductions were used to analyze the spectra. Accurate spectroscopic parameters were determined. The rotational spectra of the 13C containing species CH3CH2CN have been assigned, thus allowing the determination of the rotational and centrifugal distortion constant