Isotopic ethyl cyanide $^{\mathsf{13}}$CH$_\mathsf{3}$CH$_\mathsf{2}$CN, CH$_\mathsf{3}$$^{\mathsf{13}}$CH$_\mathsf{2}$CN, and CH$_\mathsf{3}$CH$_\mathsf{2}$$^{\mathsf{13}}$CN: laboratory rotational spectrum and detection in Orion

摘要: Context. Astronomical spectra of hot molecular clouds in the wavelength range from centimeter to submillimeter show a huge number rotational lines due emission complex organic molecules, and large fraction these are unidentified. The assignment unidentified new known molecules excited states, or their isotopologues requires good knowledge spectroscopic parameters molecules. Aims. We present experimental study properties 13 C-substituted ethyl cyanide CH 3 2 CN, CN. Methods. three species ground state have been measured frequency ranges 5 26 GHz using waveguide Fourier transform spectrometers 160 360 source-modulated spectrometer employing backward-wave oscillators (BWOs). Results. A accurate set constants has determined for each isotopic species. This permits prediction position that best suited detection with an accuracy few hundreds kHz. detected Orion IRc2 IRAM survey via several hundred lines, illustrating many "unidentified" bands definitely