We reversibly controlled phase conversion between a microdroplet of a NaClO₃ unsaturated 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

中文翻译：

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通过不饱和微滴中的光陷获“冻结” NaClO ₃亚稳态结晶态

我们可逆地控制NaClO ₃的微滴之间的相变只需将紧密聚焦的可见连续波（CW）激光照射到微滴上，即可使不饱和水溶液和亚稳态单晶（通常是自发结晶中的短命相）发生。激光照射使亚稳晶体产生并稳定生长，而没有多态性转变。这种成功的亚稳态相控制归因于光捕获诱导的成核的优势，该成核是从不饱和母液中发生的，而微滴法的优势则可以抑制导致转化的附加成核。原位观察表明，停止激光照射后晶体溶解，然而，即使晶体的尺寸大于焦点的尺寸，激光照射也能使晶体稳定。这些观察结果表明溶液/结晶相之间化学势的相对大小发生了变化。通过将晶体簇捕获在形成于晶体表面的光势中，通过促进晶体生长来促进这种变化，该光势源自通过晶体的“光传播”。我们的结果不仅揭示了多晶型物的控制，而且揭示了通过“冻结”手性结晶的动力学途径来制备寿命更长的非手性前体以用于非手性-手性转变的分析方法。这种变化可能是通过将晶体簇捕获在形成于晶体表面的光势中而促进的，该晶体势是通过“光传播”通过晶体而形成的。我们的结果不仅阐明了多晶型物的控制，而且阐明了通过“冻结”手性结晶的动力学途径来制备更长寿的非手性前体以用于非手性-手性转变分析的方法。通过将晶体簇捕获在形成于晶体表面的光势中，通过促进晶体生长来促进这种变化，该光势源自通过晶体的“光传播”。我们的结果不仅揭示了多晶型物的控制，而且揭示了通过“冻结”手性结晶的动力学途径来制备寿命更长的非手性前体以用于非手性-手性转变的分析方法。