Electronic structure and ultraviolet absorption spectrum of polyimide

The ultraviolet absorption spectra for polyimide and several polyimide model compounds have been measured and the spectroscopically parametrized CNDO/S3 model is used to provide a detailed quantitative description of the spectra. Analysis of the optical absorption spectrum yields a value of 30° for the phenylimide torsional angle in these systems. In addition, the ultraviolet absorptions are found to be intramolecular charge transfer transitions. © 1989 American Institute of Physics.