Forbidden Transitions in the Microwave Rotational Spectrum of the Tt Conformer of the N-Propanol Molecule

Abstract

A search for forbidden transitions was made in the microwave rotational spectrum of the Tt conformer of the propanol molecule (n-CH3CH2CH2OH) in the region of 37.0–78.0 GHz. The n-CH3CH2CH2OH molecule has a plane of symmetry containing μb and μa components of the dipole moment (μc = 0). On account of centrifugal distortion an induced component of the dipole moment μa, perpendicular to the symmetry plane of the molecule and leading to the appearance of previously forbidden rotational transitions, appears in such molecules. Forbidden "centrifugal transitions" of this type were found in the microwave rotational spectrum of the Tt conformer of the n-CH3CH2CH2OH molecule. The spectrum was analyzed by means of the Watson A-reduction rotational Hamiltonian. Sixty four forbidden μc transitions with rotational quantum numbers of up to J = 37 inclusive were identified.