Crystal Growth and Dissolution Dynamics of l-Phenylalanine Controlled by Solution Surface Laser Trapping

Abstract

We present sequential behavior of nucleation, growth, and dissolution of an l-phenylalanine plate-like crystal which is induced by a focused continuous-wave near-infrared laser beam in unsaturated solution. Upon the laser irradiation into the air/solution interface, the single crystal is generated from the focus and continuously grows two-dimensionally while being trapped by the laser. The crystal growth is stopped when the laser power is decreased. The crystal size is kept constant for a certain time period, and then the crystal starts dissolution. The dissolution is also induced by moving the crystal from the focus at the air/solution interface. When the crystal is shifted far from the original position where the crystallization is induced, the crystal starts dissolution at a certain distant position. Based on the demonstrations of the crystal size change during the laser manipulation, we conclude that the l-phenylalanine crystal is surrounded by a highly concentrated domain of a few hundreds of micrometers consisting of l-phenylalanine liquid-like clusters.