SITE-SPECIFIC PHOTOCHEMICAL-REACTION BY CORE ELECTRON-EXCITATION - CARBON AND OXYGEN K-EDGE FINE-STRUCTURE OF PMMA

The photon energy dependence of ion desorption from thin films of PMMA was measured in the 250-700 eV photon energy range to investigate the primary steps in radiation induced decomposition using monochromatic pulsed-synchrotron radiation. The desorption of the most intense ions; CH3+, H+, CH2+ and CHO+, depends on the nature of the electronic stat e created in the primary excitation process. The fragmentation occurs specifically around the site of the atom where the optical excitation took place. The very localized desorption of CH3+, and CH2+ at 288.7 a nd 535.6 eV, and of CHO+ at 539.3 eV can be very useful for lithograph ic applications or for future molecular electronic devices fabrication .