Nonlinear Dynamics of Mesoscopic Systems under Laser Irradiation

研究非平衡开放条件下的物理，对于理解从空间到生物的真实世界具有重要意义。因此，我们的研究目标是建立微米到毫米级的实验系统，在该实验系统中，聚焦的激光光束实现非平衡开放条件，并了解其机理。我们设计了一个实验模型系统，其中物体被聚焦的激光束禁住，另一方面，非平衡条件是通过激光的能量，即光子来实现的。我们还进行了理论模拟和数值计算，得到了以下结果：*连续激光照射下大分子/脂管结构的周期性变化。*激光照射引起微米级的动态相分离。*激光照射下液滴的有节奏的产生和消失。通过控制激光光束添加的位置来控制液滴的自发运动。我们研究了由化学能量梯度驱动的自发运动，并与激光照射的现象进行了比较，得到以下结果：*表面活性剂水溶液中玻璃衬底上油滴的自发运动*水-醇体系中醇滴的自发运动*BZ反应液滴的自发运动这些系统可视为一个非平衡开放系统，它被激光照射或化学能量梯度的能量流所保持。我们用非线性微分方程组描述了这些系统，并建立了非平衡开放系统时空自组织的新情景。

Studying on the physics under nonequilibrium open condition is important for understanding the real world from space to living organisms. Thus, the goal of our study is to build up experimental systems on the scale of micrometer to milimeter in which nonequilibrium open condition is achieved by the focused laser beam and to understand the mechanism. We have designed the experimental model systems where the object is trapped with a focused laser beam and, on the other hand, nonequilibrium condition is achieved by the energy of laser beam, i.e., photon. We have also made the theoretical modeling and numerical calculations, and we have achieved the following results :*A periodic change in the structure of a macromolecule / a lipid tube under the continuous laser irradiation.*Dynamical phase separation on the scale of micrometer induced by laser irradiation.*Rhythmic generation and disappearance of a droplet under laser irradiation*Control of spontaneous motion of a droplet by controlling the position of a laser beamIn addition, we have studied a spontaneous motion driven by the gradient of chemical energy in order to compare it with the phenomena with laser irradiation and achieved the following result.*Spontaneous motion of an oil droplet on a glass substrate in surfactant aqueous solution*Spontaneous motion of an alcohol droplet in a water-alcohol system*Spontaneous motion of a BZ reaction dropletThese systems can be regarded as a nonequilibrium open systems which is retained by the energy flow with laser irradiation or chemical energy gradient. We have described these systems with nonlinear differential equations, and have built up a new scenario for the spatio-temporal self organization in the nonequilibrium open systems.