LASER MANIPULATION AND ABLATION OF A SINGLE MICROCAPSULE IN WATER

Laser manipulation and ablation of a single microcapsule containing a pyrene/toluene solution were demonstrated for the first time. Irradiation of an individual capsule by a focused (approximately 1-mu-m) laser beam from a CW Nd3+:YAG laser (1064 nm) enabled us three-dimensional optical manipulation of the capsule in water. When a laser-trapped microcapsule was further irradiated by a 355-nm laser pulse (pulse width approximately 7 ns), deformation or ablative decomposition of the capsule was observed depending on the pulsed-laser intensity. The pyrene/toluene droplet ejected from the capsule upon laser ablation was shown to be tweezered by the 1064-nm laser beam. Spectroscopic characterization of individual capsules and droplets was achieved by a laser trapping-spectroscopy technique. Ablation mechanism was also discussed in terms of the pyrene concentration dependence of the ablation threshold energy.