[12p-N107-1~13] 3.1 Basic optics and frontier of optics

▲ [12p-N107-7] Optical trapping induced remote assembling at solution surface

〇Shuichi Toyouchi¹, Hsuan-Yin Wang¹, Hiroshi Masuhara¹ (1.National Yang Ming Chiao Tung Univ., Taiwan)

Keywords:optical trapping, interfaces, long-range interactions

We report a new optical trapping induced assembling phenomena at solution surface covering the sub-mm area. We performed optical trapping of polystyrene microparticles (MPs) with a tightly focused laser beam (size ~ 1 μm) on the solution surface. MPs formed a 2-dimenional assembly with a hexagonal closed packing (HCP) structure around the laser focus. With an increase of irradiation time, the assembly size grew more than 10 μm, and some MPs were splitted from the central assembly. Interestingly, the detached MPs reminded assembled and HCP structure even the trapping laser was not irradiated on the detached ones. These assemblies were dissolved when the trapping laser was switched off. If the trapping laser was switched on again, some assemblies were remotely formed again. The remote assembling implies that hidden long-range interactions among colloidal particles act at solution surface and potentially opens a new avenue for optical trapping induced assembling and crystallization.