SITE-SPECIFIC PHOTOCHEMICAL-REACTION OF PMMA BY CORE ELECTRON-EXCITATION

The photon energy dependence of photoion emission from solid films of poly(methyl methacrylate) was measured to investigate the primary step s in radiation induced decomposition following carbon and oxygen 1s el ectron excitations using monochromatic pulsed-synchrotron radiation. V arious ions including the monomer ion were observed. Further it was cl early found that the decomposition depends on the nature of the electr onic states created in the excitation process. Excitations of carbon 1 s electrons to pi and sigma* resonance states at 287.9 eV show remark able enhancement of the ion emission for CH+ and CH2+. In the energy r egion of oxygen 1s electron excitation, the increase of COOCH3+ ion wa s not observed due to a fragmentation of the side chain by creating ox ygen 1s hole.