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 state 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 and 535.6 eV, and of CHO+ at 539.3 eV can be very useful for lithographic applications or for future molecular electronic devices fabrication.