Microwave spectroscopy of HCOO13CH3 in the second methyl torsional excited state

Abstract

The new experimental results and analysis of the microwave spectra of HCOO13CH3 in the second methyl torsional excited state are reported. Pseudo-principal axis method (pseudo-PAM) was successfully applied to the normal methyl formate in the second torsional excited state and again applied to this isotopologue. We succeeded to assign 536 A-species transitions up to J=33 and Ka=15 and 417 E-species transitions up to J=32 and Ka=14. Thirty parameters were used to do the least-squares-analysis by using the pseudo-PAM Hamiltonian consisting of rotational, centrifugal distortion, and internal-rotational constants.