Vacuum-Ultraviolet Absorption Spectrum Of 3-Methoxyacrylonitrile

The high-resolution absorption spectrum of 3-methoxyacrylonitrile (3MAN) was measured between 5.27 and 12.59 eV using a synchrotron-based Fourier-transform spectrometer. It was related to an absolute absorption cross-section scale. Complementary calculations at the DFT-MRCl/aug-cc-pVTZ level of theory document the vertical transition energies and oscillator strengths toward the first 19 states of both the E and Z geometrical isomers of 3MAN. Comparisons with the experimental absorption spectrum reveal the similarities and differences between 3MAN, a bifunctional molecule, with acrylonitrile and methyl-vinylether, where only one functional group is present. As in acrylonitrile, several broad valence transitions were observed up to the ionization limit. They are likely associated with the extended pi-system induced by the nitrile group but might also involve sigma sigma* transitions close to the ionization limit. As in methylvinylether, Rydberg series converging to the ionization limit are absent. This is attributed to a difference in neutral and cationic geometry due to a 60 degrees rotation of the methyl group.