Soft X-ray fluorescence measurements of polyimide films

Abstract

Fluorescent X-ray emission spectroscopy has been used for the first time to study the electronic structure of polyimide films (PMDA-ODA) prepared on Si-substrates by spin-coating and ionized cluster beam deposition (ICBD) methods. The observed C Kα and O Kα X-ray emission spectra that probe the C 2p and O 2p partial density of states in the valence band, respectively, were compared with X-ray photoelectron valence band spectra. Theoretical simulations of X-ray energies and intensities for polyimide were performed with molecular orbital (MO) calculations of the model monomer, containing 41 atoms, utilizing a semi-empirical Hydrogenic Atoms in Molecules, V. 3 (HAM/3) method. Calculated Al Kα photoelectron spectra were obtained using Gaussian lineshape functions of an approximate linewidth (0.10 Ik for the model molecule): Ik=I′k−WD, as indicated for analysis of valence X-ray photoelectron spectra for 63 polymers from some of our previous work. Theoretical C Kα and O Kα X-ray emission and valence X-ray photoelectron spectra show good agreement with the experimental results, and were used to identify certain spectral features.