OPTICAL TRAPPING OF INORGANIC OXIDE NANOSHEETS COLLOIDALLY DISPERSED IN WATER: EFFECTS OF REFRACTIVITY

抄録

Optical trapping of three oxide nanosheets prepared by exfoliation of layered lepidocrocite-type titanate, hexaniobate, and fluorohectorite was carried out by the irradiation of linearly polarized laser beam, and their trapping behavior was compared in relation to the refractivity of oxide nanosheets. All of the nanosheets showed similar two-stage trapping process in enough dilute colloids where single nanosheets with their area around 50–100 µm² were trapped. The first stage was arrestment of a single nanosheet by the laser beam at the focus and orientation with its in-plane direction parallel to the propagation direction of the incident laser beam. The second stage was the rotation of arrested nanosheet with keeping the orientation parallel to the propagation direction of the laser beam to reach the alignment of nanosheet edge (longitudinal) direction in parallel to the polarization direction of the incident irradiation. Higher trapping efficiency, evaluated by trapping with weaker laser beam and shorter time for the completion of orientational change, was found for the nanosheet species with larger refractive index.