Mesoscopic Motion of Optically Trapped Particle Synchronized with Photochromic Reactions of Diarylethene Derivatives
Abstract
A photo-irradiated particle experiences photon pressure originating from the momentum change of photons. The photon pressure is classified into scattering, absorption, and gradient forces. Both the scattering and absorption forces push a particle toward light propagation. While the gradient force acts in the direction of the spatial gradient of light intensity, and when the refractive index of a target particle is larger than that of the surrounding medium, it pushes the particle in the direction of increasing the light intensity. In recent years, we have been investigating the micromechanical motion attained by mainly switching the absorption force through the change of resonance (photo-absorption) conditions of target objects using the photochemical reaction. In the paper that I will introduce in the colloquium, polymer microparticles containing diarylethene derivatives that exhibit photochromic reaction are optically trapped in water. The absorption force acting on the microparticles is modulated by UV laser irradiation, leading to successful micromechanical motion synchronizing the photochromic reaction.