Using Physical Vapor Deposition to Prepare Unusual Liquids and Unusual Glasses

在这个由化学部化学结构动力学和机制（CSDM-A）计划资助的项目中，威斯康星大学麦迪逊分校的Mark Ediger教授和亚利桑那州立大学的Ranko里切特教授使用先进的分析工具研究在真空室中制备的有机分子玻璃。眼镜在日常生活中很常见，应用范围从制药到工程材料再到手机显示屏。即便如此，玻璃有许多性质还没有得到很好的理解。Ediger教授和里切特教授正在研究由简单分子制成的眼镜，作为模型系统来回答有关眼镜的基本问题。解决这些问题可能会对技术中使用的玻璃材料产生影响。 在这个项目中，玻璃是直接从气相中制备的。 该项目研究具有两种不同液态的不寻常分子系统，以了解这是如何可能的以及如何用于生产新材料。该项目的第二个目标是了解制备玻璃的方法如何影响玻璃中分子的流动性。有一些先进的技术，如量子计算，可以受益于玻璃中流动性的降低。参与该项目的学生正在接受各种化学和物理分析工具的培训，这些工具用于表征薄玻璃膜。所学的技能和工具在许多科学和技术领域都很有价值，超出了本项目中研究的特定分子。此外，Ediger教授和他的团队参加了威斯康星州大学的大学预科学习机会计划（PEOPLE），该计划鼓励来自代表性不足背景的高中生从事科学和工程职业。该项目的重点是通过物理气相沉积制备的玻璃，这是一种已知的制造具有不寻常特性的玻璃的工艺。物理气相沉积可能是亚磷酸三苯酯（TPP）和其他系统的第二液相的捷径。AC纳米量热法和光谱椭偏法被用来研究通过这种路线制备的液体的稳定性和密度。X射线散射用于评估液体的结构。该项目还试图了解物理气相沉积如何影响玻璃态下的分子内运动。用介电谱法研究了十氢异喹啉玻璃。DHIQ显示分子内自由度，即使分子被捕获在玻璃状固体中，也可以改变偶极取向。DHIQ和具有类似分子内自由度的分子的测量提供了对气相沉积玻璃中分子运动抑制的理解。该项目可能会对有机电子中使用的非晶材料的改进产生广泛的影响，因为这里研究的分子可以作为这些材料的模型系统。除了上述先进测量技术和玻璃态有机体系的培训外，该项目资助的学生还领导了一个夏季化学教育计划，以扩大STEM学科中代表性不足的群体的参与。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project funded by the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professor Mark Ediger of the University of Wisconsin-Madison and Professor Ranko Richert of Arizona State University are using sophisticated analysis tools to study glasses of organic molecules prepared inside a vacuum chamber. Glasses are common in everyday life with applications ranging from pharmaceuticals to engineering materials to cell phone displays. Even so, glasses have many properties that are not well understood. Professors Ediger and Richert are studying glasses made of simple molecules to serve as model systems to answer fundamental questions about glasses. Answering these questions can have an impact on glassy materials used in technology. In this project, glasses are prepared directly from the vapor phase. This project investigates unusual molecular systems that have two distinct liquid states to understand how this is possible and how it might be used to produce new materials. A second goal of this project is to understand how the method of preparing a glass can impact the mobility of molecules in the glass. There are advanced technologies such as quantum computing that can benefit from decreased mobility in glass. The students involved in this project are being trained in a wide variety of chemical and physical analysis tools which are used to characterize thin glassy films. The skills and tools learned are valuable in many areas of science and technology beyond the specific molecules studied in this project. In addition, Professor Ediger and his group participate in a Pre-college Enrichment Opportunity Program for Learning Excellence (PEOPLE)program at University of Wisconsin that encourages careers in science and engineering of high school students from underrepresented backgrounds. The project focuses on glasses prepared by physical vapor deposition, a process known to create glasses with unusual properties. It is likely that physical vapor deposition may serve as a shortcut to the second liquid phase of triphenyl phosphite (TPP) and other systems. AC nanocalorimetry and spectroscopic ellipsometry are used to study the stability and density of the liquids prepared by this route. X-ray scattering is used to assess the structure of the liquids. This project also seeks to understand how physical vapor deposition affects intramolecular motions in the glassy state. Dielectric spectroscopy is used to study glasses of decahydroisoquinoline (DHIQ). DHIQ displays intramolecular degrees of freedom which can alter the dipole orientation even while the molecule is trapped in a glassy solid. Measurements of DHIQ and molecules with similar intramolecular degrees of freedom provide understanding about suppression of molecular motion in vapor-deposited glasses. This project may have a broad impact on the improvement of amorphous materials used in organic electronics, since the molecules studied here serve as model systems for those materials. In addition to the aforementioned training in advanced measurement techniques and glassy organic systems, the students funded by this project also lead a summer chemistry education program in broadening participation of under-represented groups in STEM disciplines.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.