High resolution x-ray photoelectron spectroscopy and INDO/S-Cl study of the core electron shakeup states of pyromellitic dianhydride-4,4 '-oxydianiline polyimide

Pyromellitic dianhydride-4,4'-oxydianiline (PMDA-ODA) polyimide films have been studied using high resolution x-ray photoelectron spectroscopy and mod el semi-empirical INDO/S-CI calculations. Experimental and theoretical C 1s , N 1s, and O 1s spectra are presented, and found to be in good agreement w ith each other. Shakeup features of the spectra are identified, and their e lectronic nature analyzed theoretically. The highly nonstoichiometric ratio between the carbonyl and the ether O 1s main peaks is quantitatively expla ined by the calculations, where the nonstoichiometry is shown to be the res ult of stronger carbonyl than ether shakeup. Conformational effects on the shakeup spectra, due to torsion between the PMDA and ODA units, were invest igated theoretically and found to be small for PMDA-ODA. (C) 1999 American Vacuum Society. [S0734-2101(99)02705-0].