Time-resolved microspectroscopy and interferometry of organic mesoscopic materials†

Abstract

The characterization of mesoscopic materials and analysis of their physical and chemical processes were performed by advanced laser and optical techniques. By using a laser manipulation technique, a micrometre-sized particle in solution was chosen and fixed at the focal point of a microscope by the photon pressure of a focused near-infrared laser beam. The laser trapping potential exerted on the single microparticle was thus analysed. A picosecond time-resolved fluorescence microspectroscopic system was applied to measure picosecond lasing dynamics of a single particle, and the results are discussed. The electric charge on a single microparticle in solution and the adhesion force between the particle and a quartz plate were also determined by the laser manipulation method. Mesoscopic thin films undergo morphological change and ablation on intense laser pulse excitation. The photothermal expansion–contraction and photodecomposition behaviour of a surface layer was interrogated by means of time-resolved interferometry developed by combining a nanosecond time-resolved laser and Michelson interferometry.