The processes of radical formation in N-methylmorpholine-N-oxide monohydrate (NMMO) and cellulose/NMMO solutions were studied by ESR at 77 K under high-power UV (lambda = 248 nm) excimer laser flash photolysis. Radicals mainly generated were attributed to the nitroxide type radicals -CH2-NO*-CH2- and -CH2-NO*-CH3 at the first step and methyl *CH3 and formyl *CHO radicals at the second step of the photoreaction. Kinetic studies of these radicals revealed that formation and recombination rates of the radicals depend on the cellulose concentration in cellulose/NMMO solutions and the concentration of additional ingredients, e.g. Fe(II) and propyl gallate. Even at frozen state temperature, acceleration or quenching of radical reaction processes was found. The proposed scheme of UV light-induced NMMO degradation during irradiation based on ESR data correlates well with independently obtained results based on high-performance liquid chromatography (HPLC). The analysis of degradation products by HPLC, e.g. aminoethanol and acetaldehyde, supports the assumption concerning a radical-initiated ring opening of NMMO.
It has been demonstrated that the laser irradiation of the specialy synthesized polymer Poly(bis-alkylthioacetylene)-PATAC induces the generation of highly permanently conducting sites in the material which remains an insulator in the unexposed areas. Conductivity changes by 16 orders of magnitude (-200 Scm-1) have been observed. The conductivity values of the final reaction products are in the level of a heavily doped semiconductor.These conductivity values make the PATAC coated materials suitable for microelectronic applications such as the laser direct imaging of conducting paths and circuit structures.
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