Chemistry at the Spatial Limit

空间极限的化学

• 批准号: 0102887
• 负责人: Wilson Ho
• 金额: $ 75万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-15 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0102887&HistoricalAwards=false
• 关键词: Chemistry; Spatial; Limit

The aim of this research is to obtain detailed descriptions of single atoms and molecules. These experiments provide the basis for understanding chemical and physical processes at surfaces and properties of nanostructured condensed matter and molecular materials. Low temperature scanning tunneling microscopes (STM) are used to image, manipulate, chemically modify, and spectroscopically identify individual atoms and molecules. The development of the single molecule vibrational probe by inelastic electron tunneling spectroscopy (STM-IETS) provides a new analytical technique with unprecedented spatial resolution. It is now possible to investigate chemistry at the spatial limit with the STM; the results provide a view of chemistry not possible by studying an ensemble of molecules. In particular, the fundamental motions in molecules (vibration, rotation, translation), the coupling of tunneling electrons to nuclear motions (charge and energy transfers), and electrical conductivity (as related to molecular electronics) can be studied with single molecule sensitivity. The tunnel junction forms a novel nanoreactor in which the tip and the substrate can be used together to carry out unimolecular dissociation and bimolecular reactions. The research covers selected chemical systems from the lightest element (hydrogen atoms) to diatomic (carbon monoxide) and larger organic molecules (thios) on metal surfaces. These studies will lead to the development of a method to detect single electron spins in individual atoms and molecules by the STM. A thin film of magnetic metal (iron, gadolinium) is evaporated on the STM tip to provide a source of spin polarized electrons. The study of single and small aggregates of Manganese, Cobalt, Nickel, and Iron atoms, nitric oxide and nitric oxide dimers, 1,1-diphenyl-2-picryl-hydrazyl (DPPH), and other molecules with unpaired spins provides a new way to understand magnetism at the atomic scale and illuminates the role of the electron spins in chemistry. Overall, these experiments are intended to illuminate general experimental procedures and scientific understandings. The research on solid surfaces is fundamental in nature and provides a foundation for a broader understanding of chemistry in the gas phase, solution, and other condensed media.%%%An integral part of the proposed research involves the scientific training and development of undergraduate and graduate students. Since the STMs (microscope, electronics, and software) are homemade, the students have a unique opportunity to be involved in the design and construction of new generations of STMs. In addition, UC Irvine has established centers to reach out to local K-12 schools which have large populations of underrepresented groups. The P.I. will teach a special topics course on "Nanoscience" which will attract an interdisciplinary group of students from physics, chemistry, biology, and engineering. While the emphasis of the proposed research is to obtain a fundamental understanding, the implications for futuristic technologies are apparent, and students trained in these areas will be highly competitive in the job market. This project is being co-funded by the Chemistry Division/Analytical and Surface Chemistry Program and the Division of Materials Research/Solid State Chemistry Program.

这项研究的目的是获得对单个原子和分子的详细描述。这些实验为理解表面的化学和物理过程以及纳米结构凝聚态物质和分子材料的性质提供了基础。低温扫描隧道显微镜(STM)用于成像、操纵、化学修饰和光谱识别单个原子和分子。非弹性电子隧道谱(STM-IETS)单分子振动探头的发展提供了一种新的空间分辨率分析技术。现在，用扫描隧道显微镜在空间极限上研究化学是可能的；结果提供了一种通过研究分子系综所不可能的化学观点。特别是，分子中的基本运动(振动、旋转、平移)，隧穿电子与核运动的耦合(电荷和能量转移)，以及电导率(与分子电子学有关)可以用单分子灵敏度来研究。隧道结形成了一种新型的纳米反应器，其中针尖和衬底可以一起用于进行单分子解离和双分子反应。这项研究涵盖了选定的化学体系，从最轻的元素(氢原子)到双原子(一氧化碳)和金属表面的较大有机分子(硫代)。这些研究将导致开发一种用扫描隧道显微镜检测单个原子和分子中的单电子自旋的方法。在STM针尖上蒸发一层磁性金属(铁、Gd)薄膜，以提供自旋极化电子源。对锰、钴、镍和铁原子的单个和小聚集体、一氧化氮和一氧化氮二聚体、1，1-二苯基-2-苦皮酰肼(DPPH)和其他具有不成对自旋的分子的研究提供了一种在原子尺度上理解磁性的新途径，并阐明了电子自旋在化学中的作用。总体而言，这些实验旨在阐明一般的实验程序和科学理解。固体表面的研究在本质上是基础性的，为更广泛地了解气相、溶液和其他凝聚介质中的化学提供了基础。%拟议研究的一个组成部分涉及本科生和研究生的科学培训和发展。由于STM(显微镜、电子学和软件)是自制的，学生们有一个独特的机会来参与新一代STM的设计和建造。此外，加州大学欧文分校还建立了中心，以接触当地K-12学校，这些学校有大量代表不足的群体。P.I.将开设一门关于“纳米科学”的专题课程，吸引来自物理、化学、生物和工程学的跨学科学生。虽然拟议研究的重点是获得基本的理解，但对未来技术的影响是显而易见的，受过这些领域培训的学生将在就业市场上具有很强的竞争力。该项目由化学部/分析和表面化学计划和材料研究/固态化学计划共同资助。