レーザーアブレーション機構解明のためのナノ秒形態観察・分光システムと解析法の確立

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Photophysical and photochemical phenomena due to interactions of materials with light have received much attention and the 21st century is considered to be "Century of Light". We have devoted our efforts to the studies on organic materials including films, microcrystalline powders, polymer microspheres, and so on by ultrafast spectroscopy, microspectroscopy, photoreaction, and optical manipulation, during which we found that materials often undergo morphological changes due to high intensity laser excitation. This morphological dynamics is very interesting and important not only from photophysical and photochemical viewpoints but also for elucidating the dynamic aspects of structures and properties of materials.In the present work, we have developed nanosecond interferometry by combining Michelson interferometry with nanosecond excitation and probe lasers. The spatial and temporal resolutions of our system are 20 nm and 10 ns, respectively. Morphological dynamics revealed by the interferometry is compared with time-resolved absorption and fluorescence spectroscopic data and considered in detail, which is opening a new stage of molecular photoscience.Development of a new methodologyEstablishment of photothermal ablation mechanism by "cyclic multiphotonic absorption"Establishment of photochemical ablation mechanismExpansion/contraction dynamics of polymer filmPhotodecomposition reaction and etching dynamics of polymers