Chemical bonding analysis of electron-sensitive polymers by EELS

We have performed EELS analysis of poly(methyl metacrylate) (PMMA) in the a nalytical TEM in order to evaluate the possibility to obtain chemical infor mation on electron sensitive polymers. In the acquired spectra, we propose an identification to the different chemical bondings in agreement with mole cular orbital calculations and with previous XANES experiments. Moreover, m ain results confirm that PMMA is very sensitive to electrons with a critica l dose of about 10(2) C m(-2). The evolution of the EELS spectra of PMMA du ring irradiation damage is found to be slightly dependant on the molecular weight of the polymer. Finally, a degradation process in agreement with EEL S data is proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.