Single Molecule and Nonlinear Spectroscopic Studies of Water and Other Liquids Above and Below the Glass Transition

玻璃化转变之上和之下的水和其他液体的单分子和非线性光谱研究

• 批准号: 0226913
• 负责人: Ryszard Jankowiak
• 金额: $ 34.5万
• 依托单位: Iowa State University
• 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: 2002-12-01 至 2006-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0226913&HistoricalAwards=false
• 关键词: Single; Molecule; Nonlinear; Spectroscopic; Studies

The goal of the is project is to attain a deeper molecular level understanding of the dramatic slowing down of the molecular relaxation processes (rotations, translations) as the temperature of a supercooled liquid approaches the glass transition temperature (Tg). This challenging problem on the nature of glass and the glass transition remains as one of the most important in solid-state physics and -chemistry. No microscopic theory exists that captures all salient features of the kinetic glass formation process that marks the onset of non-ergodicity. The experimental approach is unique in that it uses three laser-based spectroscopies; single molecule (SMS), photon echo (PES) and nonphotochemical hole burning (NPHB). The liquids to be studied are water, methanol and ethanol (probe molecule Al-phthalocyanine tetrasulphonate) at temperatures below and above Tg. SMS reports on molecular rotational relaxation over a ~1-4000 second time period while NPHB and PES report on optical dephasing of probe transitions on a picosecond time scale. A novel hyperquenching apparatus will be used to prepare the glasses at low temperatures which can then be warned to Tg and temperatures above Tg. The above liquids will also be studied in confined spaces of porous materials (pore sizes ranging from a few nanometers to ~ 100 nanometers). Here water is particularly interesting since the non-freezable water in contact with a pore surface is a model for biological water bound to proteins. The research will provide students with an excellent training because of the cutting edge experimental techniques to be used and because the research is both challenging and importantThis unique experimental approach employing three state-of-the-art laser spectroscopies and a novel apparatus for forming a glass by cooling small liquid droplets at a rate of a million degrees per second will be used to attain a molecular level understanding of the glass transition. The data will provide new insights on how the motions of molecules dramatically slow down as the liquid is cooled towards Tg. What is learned for three important liquids (water, ethanol, and methanol) may well lead to better glasses for technological applications. Because the research is cutting-edge it will provide graduate students and postdoctoral researchers with an excellent training serve them well as independent researchers with an excellent training serve them well as independent researchers in an area of high technological importance.

该项目的目标是实现一个更深层次的分子水平的理解的戏剧性放缓的分子松弛过程（旋转，平移）的温度过冷液体接近玻璃化转变温度（Tg）。 玻璃的性质和玻璃化转变是固体物理和化学中最重要的问题之一。 没有微观理论存在，捕捉所有显着特征的动力学玻璃形成过程，标志着非遍历性的开始。 实验方法的独特之处在于它使用了三种基于激光的光谱：单分子（SMS），光子回波（PES）和非光化学空穴燃烧（NPHB）。 待研究的液体是在低于和高于Tg的温度下的水、甲醇和乙醇（探针分子四磺酸铝酞菁）。 SMS报告了分子旋转弛豫超过~1-4000秒的时间段，而NPHB和PES报告了探测跃迁在皮秒时间尺度上的光学退相。 一种新型的超淬冷装置将用于在低温下制备玻璃，然后可以将其警告到Tg和Tg以上的温度。 上述液体还将在多孔材料（孔径范围从几纳米到~ 100纳米）的密闭空间中进行研究。 这里，水是特别令人感兴趣的，因为与孔表面接触的不可冻结的水是与蛋白质结合的生物水的模型。 这项研究将为学生提供一个很好的培训，因为尖端的实验技术要使用，因为这项研究是既具有挑战性和重要性，这种独特的实验方法采用三个国家的-先进的激光光谱学和一种通过以每秒一百万度的速度冷却小液滴来形成玻璃的新装置将被用来获得对玻璃的分子水平的理解。过渡 这些数据将为分子运动如何随着液体冷却到Tg而急剧减慢提供新的见解。 对三种重要液体（水、乙醇和甲醇）的研究可能会为技术应用带来更好的玻璃。 因为这项研究是尖端的，它将为研究生和博士后研究人员提供良好的培训，为他们提供良好的培训，为他们提供独立的研究人员，为他们提供高技术重要性领域的独立研究人员。