We systematically studied pseudopolymorphism (anhydrate- and trihydrate-form) of sodium acetate induced by focused irradiation with ultrashort laser pulses into a supersaturated aqueous solution. We found that both anhydrate and trihydrate crystals were obtained with femtosecond (fs) laser pulses, while anhydrate crystals were preferentially generated with picosecond (ps) laser pulses. In addition, the maximum value of the crystallization probability with femtosecond laser pulses (∼100%) was higher than that with picosecond laser pulses (∼60%). We found that the laser parameter dependence of the crystallization behavior of sodium acetate can be well explained from a viewpoint of the temperature–concentration diagram of sodium acetate and the interplay of cavitation bubble generation (promoting nucleation) and temperature elevation (suppressing nucleation). We foresee that this study can provide basic insights into the underlying mechanism of the laser-induced pseudopolymorphism, which can allow for the optimization of laser parameters for the fine-tuned control of crystallization from aqueous solutions.

中文翻译：

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超短激光脉冲聚焦辐照诱导过饱和水溶液中乙酸钠的假多晶型现象


我们系统地研究了超短激光脉冲聚焦照射过饱和水溶液诱导的乙酸钠的假多晶型（无水物和三水物形式）。我们发现无水物和三水物晶体都是用飞秒（fs）激光脉冲获得的，而无水物晶体则优先用皮秒（ps）激光脉冲生成。此外，飞秒激光脉冲的结晶概率最大值（~100%）高于皮秒激光脉冲的结晶概率最大值（~60%）。我们发现，从乙酸钠的温度-浓度图以及空化气泡产生（促进成核）和温度升高（抑制成核）的相互作用的角度来看，乙酸钠结晶行为的激光参数依赖性可以得到很好的解释。我们预计这项研究可以为激光诱导假多晶型的潜在机制提供基本见解，从而可以优化激光参数以微调控制水溶液的结晶。