The vibrational structure of the UV spectrum and the internal rotation potential function of the β,β-dimethylacrolein molecule

The vibrational structure of the UV spectrum of beta,beta-dimethylacrolein was analyzed to construct the Deslandres tables for the trans and cis isomers of this molecule. The torsional levels were determined up to nu" = 5 for both isomers in the around state and up to V = 5 and 2 for the trans and cis isomers, respectively, in the excited electronic state (S-1). The harmonic frequencies and anharmonicity coefficients of torsional vibrations were calculated for both isomeric forms in the S-0 and S-1 states. The experimental torsional levels of both isomeric forms, the experimental energy differences, and the geometric parameters obtained in quantum-mechanical calculations were used to calculate the V-n parameters of the V(phi) potential function in both electronic states of the isomers.