Non-Photochemical Laser-Induced Nucleation to Provide Crystallization-on-Demand and to Control Crystal Structure

非光化学激光诱导成核以提供按需结晶并控制晶体结构

• 批准号: 0210065
• 负责人: Bruce Garetz
• 金额: $ 28.43万
• 依托单位: Polytechnic University of New York
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0210065&HistoricalAwards=false
• 关键词: Non; Photochemical; Laser; Induced; Nucleation

This grant will be used to develop non-photochemical laser-induced nucleation as amethod for providing nucleation-on-demand, for controlling crystal structure, and forimproving the current understanding of nucleation from solution. The basis of thistechnique is the discovery, made by the PIs several years ago, that intense near-infraredlaser pulses could induce crystallization in aged supersaturated solutions of small organicmolecules. In cases studied so far, laser-induced nucleation enhances the rate ofnucleation by a factor of 10 13 . Even more intriguing is the case of aqueous glycine,which crystallizes into two different polymorphs depending on the laser polarization state(linear vs. circular), which implicates the optical electric field as being responsible for thephenomenon. This "polarization switching" of polymorphs represents a clean method forcontrolling crystal structure. It is hypothesized that the oscillating electric field of thelight is aligning solute molecules in a pre-nucleating cluster, aiding its organization into aparticular crystal structure. The method also has the potential of creating newpolymorphs of some substances. New polymorphs constitute novel materials that mayhave important industrial applications.Over the next three years the PIs propose to gain a better understanding of the mechanismof non-photochemical laser-induced nucleation, by systematically studying itsdependence on illumination parameters such as intensity, wavelength, laser pulse widthand polarization state. With the same goal, they will also explore the effect of a strongstatic electric field on supersaturated solutions. Other experiments would focus onscreening a large number of solvent/solute systems, as well as melts, to correlate the formof the inducing electric field to the crystal structure that is induced. Such screeningwould also include a search for new polymorphs.

这笔拨款将用于发展非光化学激光诱导成核，作为提供按需成核的方法，用于控制晶体结构，并改善目前对溶液成核的理解。这项技术的基础是几年前pi的一项发现，即强烈的近红外激光脉冲可以在老化的小有机分子过饱和溶液中诱导结晶。在迄今所研究的案例中，激光诱导成核使成核速率提高了10倍。更有趣的是水甘氨酸的情况，它结晶成两种不同的多晶型取决于激光偏振状态（线性或圆形），这意味着光学电场是造成这种现象的原因。这种多晶的“极化开关”代表了一种控制晶体结构的干净方法。据推测，光的振荡电场使溶质分子在预成核团簇中排列，帮助其组织成特定的晶体结构。该方法还具有创造某些物质的新多态性的潜力。新的多晶构成了可能具有重要工业应用的新型材料。在接下来的三年里，PIs计划通过系统地研究非光化学激光诱导成核的机理，如强度、波长、激光脉冲宽度和偏振态。为了实现同样的目标，他们还将探索强静电场对过饱和溶液的影响。其他实验将集中于筛选大量的溶剂/溶质体系，以及熔体，以将感应电场的形式与被诱导的晶体结构联系起来。这种筛选还将包括寻找新的多态性。