Parahydrogen Matrix Isolation Infrared Spectroscopy and Kinetics

仲氢基质分离红外光谱和动力学

• 批准号: 2101719
• 负责人: David Anderson
• 金额: $ 50万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2101719&HistoricalAwards=false
• 关键词: Parahydrogen; Matrix; Isolation; Infrared; Spectroscopy

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program in the Division of Chemistry, Professor David T. Anderson and his group at the University of Wyoming are using extremely cold crystals made from molecular hydrogen as a reaction vessel to investigate chemistry at low temperatures. The first thrust of the research project examines the diffusion and reactivity of hydrogen atoms. At extremely low temperatures (-457°F), hydrogen atoms are better described as matter waves instead of particles, which has a major impact on how they diffuse through the crystal and react chemically with other species. Chemistry is transformed under these low-temperature conditions into the fully quantum mechanical regime where unexpected chemical behavior can be discovered. The second thrust of the work involves experimental studies of nuclear spin states in polyatomic molecules that undergo rapid cooling, photochemistry, or chemical reactions. Nuclear spin refers to the internal state of an atom, and sometimes has an orientation. Certain molecules, like water, come in two different forms, one where the two hydrogen atoms have their nuclear spins aligned in the same direction, and the other with the two hydrogen atom spins aligned in opposite directions. These different nuclear spin isomers of water have different magnetic properties. The research team led by Professor Anderson is examining to what extent nuclear spin is conserved during various physical and chemical processes, with the goal of learning how to use nuclear spin to control chemical reactions and to enhance magnetic imaging techniques. This experimental work uses a custom-designed cryogenic apparatus to synthesize cryocrystals of para-hydrogen (a specific nuclear spin isomer of molecular hydrogen) doped with parts per million concentrations of chemical impurities at temperatures in the 1.5 to 5 K range. Hydrogen atoms are created in situ using a variety of ultraviolet light sources and the ensuing reaction kinetics are measured using high-resolution Fourier-transform infrared spectroscopy. Professor Anderson and his group utilize a liquid helium cryostat to achieve such low temperatures and have built a dedicated helium recovery system to recycle the spent helium gas to minimize supply costs. The students working with Professor Anderson gain experience using sophisticated methods in experimental physical chemistry that probe the physical and chemical properties of quantum materials, materials whose properties are dominated by the laws of quantum mechanics. The involvement of students in the research has a significant impact by training future scientists in the techniques of low-temperature chemistry and the quantum-mechanical manipulation of matter.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.

在化学结构，动力学和机制-A（CSDM-A）计划中的支持下，戴维·T·安德森教授及其在怀俄明大学的小组使用了由分子氢作为反应容器制成的极冷晶体，以在低温下研究化学。研究项目的第一个推力是氢原子的扩散和反应性。在极低的温度（-457°F）下，更好地描述氢原子是物质波而不是颗粒，这对它们如何通过晶体扩散并与其他物种进行化学反应产生了重大影响。化学在这些低温条件下转化为完全量子力的机械状态，可以发现意外的化学行为。这项工作的第二个力量涉及对经历快速冷却，光化学或化学反应的多原子分子中核自旋态的实验研究。核旋转是指原子的内部状态，有时具有方向。某些分子（例如水）有两种不同的形式，一种分子的两个氢原子的核自旋朝着相同的方向排列，另一个与两个氢原子旋转在相反方向排列在一起。这些不同的水的核自旋异构体具有不同的磁性特性。由安德森（Anderson）教授领导的研究团队正在研究在各种物理和化学过程中核旋在多大程度上保存的程度，目的是学习如何使用核自旋来控制化学反应并增强磁成像技术。这项实验性工作使用定制设计的低温设备来合成para-Hydrogen的冷冻晶体（一种特定的分子氢的核自旋异构体），在1.5至5 K范围内的温度下，掺杂了每百万个浓度的化学杂质。氢原子是使用多种紫外线原位创建的，并使用高分辨率傅立叶转变红外光谱法测量了反应动力学。安德森教授及其小组利用液体氦低温恒温器来达到如此低的温度，并建立了专用的氦回收系统来回收用过的氦气，以最大程度地降低供应成本。与安德森教授一起工作的学生利用实验性化学中的复杂方法获得了经验，这些方法探测了量子材料的物理和化学特性，这些材料的特性以量子力学定律为主。学生参与研究的参与通过培训未来的科学家对低温化学技术和物质的量子力学操纵的技术产生了重大影响。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响审查标准来通过评估来诚实地支持。

项目成果

Infrared Spectroscopic Studies of Oxygen Atom Quantum Diffusion in Solid Parahydrogen

固体仲氢中氧原子量子扩散的红外光谱研究

• DOI: 10.1021/acs.jpca.3c00266
• 发表时间: 2023
• 期刊: The Journal of Physical Chemistry A
• 作者: Muddasser, Ibrahim;Nguyen, Anh H.;Strom, Aaron I.;Hardee, Aaron M.;Pluid, Bryan G.;Anderson, David T.
• 通讯作者: Anderson, David T.