Pulsed Laser-Induced Nucleation of Sodium Chlorate at High Energy Densities
Pulsed Laser-Induced Nucleation of Sodium Chlorate at High Energy Densities
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DOI：
10.1021/acs.cgd.9b00951
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发表时间：
2019-12-01
影响因子：
3.8
通讯作者：
Alexander, Andrew J.
中科院分区：
文献类型：
--
作者：
Barber, Eleanor R.;Kinney, Nina L. H.;Alexander, Andrew J.
本文报道了在高能量密度(420kJ·cm~(-2))下，用聚焦纳秒激光脉冲研究氯酸钠在过饱和水溶液中的激光成核。在单个激光脉冲照射下，观察到了以发光等离子体的形式出现的光学击穿，并产生了大量的微泡。在观测的基础上，我们估计溶液中光学击穿的能量阈值为70J cm(-2)。值得注意的是，即使在高能量密度下，单个激光脉冲平均也只产生一到两个晶体。平均每个样品(3 cm(3))的晶体数为1.5(532 Nm)和1.8(1064 Nm)。研究了左圆偏振和右圆偏振光对立方(I相)氯酸钠晶体右旋(D)和左旋(L)对映体成核的影响。圆偏振的螺旋度与对映体的手性之间没有明显的相关性。结果与非手性单斜晶系III成核，然后固-固相变为手性氯酸钠立方相I的机理是一致的，尽管这种转变没有被直接观察到。在高脉冲能量密度下使用单脉冲LIN在探索晶型或生产用于分析的单晶中可能是有用的。
We report on a study of laser-induced nucleation (LIN) of sodium chlorate in supersaturated aqueous solutions using focused nanosecond laser pulses at high energy densities (420 kJ cm(-2)). On irradiation with a single laser pulse, optical breakdown was observed in the form of a luminous plasma, and numerous microbubbles were produced. On the basis of the observations, we estimate the energy threshold for optical breakdown in the solutions to be 70 J cm(-2). Remarkably, even at high energy densities, single laser pulses produced on average only one or two crystals. The mean number of crystals obtained was 1.5 (532 nm) and 1.8 (1064 nm) per sample (3 cm(3)). The effect of left circularly polarized (LCP) and right circularly polarized (RCP) light on the nucleation of dextrorotatory (d) versus levorotatory (l) enantiomorphs of cubic (phase I) sodium chlorate crystals was investigated. No significant correlation between the helicity of circular polarization and the chirality of enantiomorph was observed. The results are consistent with a mechanism involving nucleation of the achiral monoclinic phase III followed by solid-solid transformation to the chiral cubic phase I of sodium chlorate, although this transformation was not observed directly. The use of single-pulse LIN at high pulse energy densities may be useful in the exploration of polymorphs or in the production of single crystals for analysis.