Freezing of NaClO3 Metastable Crystalline State by Optical Trapping in Unsaturated Microdroplet
Freezing of NaClO3 Metastable Crystalline State by Optical Trapping in Unsaturated Microdroplet
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不饱和微滴中光捕获冻结 NaClO3 亚稳态晶态
DOI：
10.1021/acs.cgd.7b01116
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
K. Miyamoto and T. Omatsu
中科院分区：
文献类型：
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作者：
H. Niinomi;T. Sugiyama;K. Miyamoto and T. Omatsu
我们可逆地控制微滴的NaClO 3不饱和水溶液和亚稳单晶，这通常是一个短暂的阶段，在自发结晶，简单地通过照射一个紧密聚焦的可见连续波（CW）激光的微滴之间的相转换。激光照射允许亚稳晶体产生并稳定生长而没有多晶型转变。这种成功的亚稳相控制归因于光学捕获诱导成核的优势（成核发生在不饱和母液中）和微滴方法的优势（抑制导致转变的额外成核）的结合。原位观察表明，当停止激光照射时，晶体溶解，而即使晶体的尺寸变得大于焦点的尺寸，激光照射也使晶体稳定。这些观察结果表明，溶液/结晶相之间的化学势的相对大小的变化。这种变化可能是通过晶体生长促进的，通过捕获的晶体簇在光学势阱中形成的晶体表面上起源于“光传播”通过晶体。我们的研究结果不仅为多晶型控制提供了参考，而且为通过“冻结”手性结晶动力学途径制备用于分析非手性-手性转变的长寿命非手性前体提供了方法
We reversibly controlled phase conversion between a microdroplet of a NaClO3unsaturated aqueous solution and a metastable single crystal, which is usually a short-lived phase in spontaneous crystallization, simply by irradiating a tightly focused visible continuous-wave (CW) laser to the microdroplet. The laser irradiation allowed the metastable crystal to generate and stably grow without a polymorphic transformation. This successful metastable phase control is attributed to the combination of the advantage of optical trapping-induced nucleation that nucleation takes place from unsaturated mother solution and the advantage of microdroplet method, which suppresses additional nucleation leading to the transformation. In situ observation shows the crystal dissolves when the laser irradiation is stopped, whereas the laser irradiation stabilizes the crystal even if the size of the crystal becomes larger than that of focal spot. These observations indicate that a change in the relative magnitudes of chemical potentials between solution/crystalline phases. This change is possibly promoted via crystal growth by trapping of crystalline clusters in optical potential well formed on a crystal surfaces originating from “light propagation” through the crystal. Our results shed a light not only on polymorph control but also on a method to prepare a longer-lived achiral precursor for analysis on achiral–chiral transition by “freezing” a kinetic pathway of chiral crystallization