SPATIALLY SELECTIVE SURFACE DISSOCIATION OF MACROMOLECULES UNDER THE ACTION OF RESONANT IR LASER-RADIATION

We revealed and investigated spatially selective dissociation of polym er macromolecules that selectively absorb radiation with lambda = 2.8 mu m (the band of stretching vibrations of the OH group) under the act ion of resonant laser pulses produced by an optical parametric oscilla tor. The nonequilibrium effect became possible because of specific fea tures of the permolecular structure of polymers, such as the aggregati on of macromolecules into associates (clusters) or the presence of mic roblocks in polymer chains. Selective absorption of IR radiation by th ese structure formations results in the localization of vibrational en ergy in these formations during the time comparable with characteristi c dissociation times. Analysis of the kinetics of selective dissociati on showed that the characteristic time of relaxation of vibrational en ergy from excited clusters is 10(-9) s, which is considerably greater than the characteristics times of intra- and intermolecular exchange f or condensed media. It is demonstrated that the selectivity degree of dissociation grows with the decrease in the ordering degree of the pac king of macromolecules. This finding indicates a considerable influenc e of hydrogen bonds on the spatial deactivation of excited macromolecu les.