Optically reversible deformation of azobenzene particles prepared by a colloidal method

Optical reversibility of deformation of azobenzene particles prepared by a colloidal method is demonstrated. Linearly polarized laser light modifies the shape of the azo particles through photoisomerization of the azo molecules. We found that the oblique incidence of a single laser beam can reversibly deform the azo particles into shapes, including spherical, elliptical, and rod shapes, through simple adjustment of the polarization direction and irradiation time of the laser light. The direction of the long axis of the ellipsoid was sequentially controlled by selecting the polarization direction of obliquely incident laser light, although the normal incidence never rotated the ellipsoidal direction under any polarization direction. The reversibility of the changes in the azo particle shape was confirmed in cyclic optical deformation experiments.