The microwave and submillimeterwave spectrum of 13C1-methyl formate in its ground torsional state (H13COOCH3)

The rotational spectrum of 13C1 methyl formate (H13COOCH3) has been observed in the frequency range 7-610 GHz. Two hundred and ninety one transitions up to J=58 (Kmax=24) were assigned to the A-species of the ground torsional state. They could be fitted to a standard Watsonian involving 19 parameters (up to one decic centrifugal distortion constant). About 260 E-transitions were also assigned. A global analysis of all these transitions using the internal axis method gave a satisfactory fit permitting to determine the three internal rotation parameters (Iα=3.132(4) μÅ2, V3=4912(6) J/mol and ∠(i,a)=52.30(5)°, which is the angle between the principal axis a and the internal rotation axis i) and allowing us to make an accurate prediction of the rotational spectrum.