Atomic Scale Chemistry

非技术摘要本研究的主要目的是利用国产的扫描隧道显微镜（STM）在原子尺度上研究化学。 通过探测单个原子和分子，它们与环境的相互作用以及组装成更复杂的纳米结构，应该可以获得关于化学键合，结构和反应性的新知识。 这些知识将使化学更好地控制，允许合成新分子，组装以前未知的系统，并实现技术创新。 由于这些实验在量子力学水平上探索化学，因此其中一些结果应该作为现代物理和化学课程中目前教授的问题和概念的物理实现。 同样重要的是STM的成像能力所提供的可视化。 原子、分子和它们的组合体以前只能用文字和图片来想象，现在可以成像和可视化。 这些图像给公众留下了深刻的印象，并有效地推广到K-12和大学生。 对单个原子和分子的拟议研究是一个重要的主题，因为它们构成了我们周围一切的基石。 此外，看到单个原子和分子及其相互作用使公众更接近于对新纳米技术的理解和欣赏。 总之，这个项目推进了我们对科学和技术的基本理解，并通过可视化每一个问题是什么和如何来服务于学生和公众的有效推广和教育。该项目由化学部和材料研究部共同资助。技术摘要：两台独特的国产低温扫描隧道显微镜（STM）用于探测单分子及其组装体的内部。 其中一个STM包含RF激励源，并浸入700高斯的低磁场中，在15 K下工作。 第二个STM达到1 K，并处于高达9特斯拉的磁场中。 这些独特的STM使新的实验得以进行，包括原子尺度的自旋性质和磁性，高分辨率光谱学和量子隧穿。 该系统扩展了很大的尺寸范围，从单个氢原子到多原子含金属的有机分子。 通过探测单个分子的内部，可以了解它们的内部机制，包括电子振动耦合，能量和电子转移，自旋结构和耦合，以及导致键解离或形成的核运动。 仪器的开发和改进仍然是该项目的一项重要使命，使尖端研究技术得以实现。 这两台STM的所有方面都是自制的，包括显微镜、电子设备和软件。 学生获得宝贵的实验室技能和解决问题的经验。 这些知识为他们提供了进入新领域和解决可能与他们的大学培训远程连接的问题的能力，在他们未来的职业生涯中很好地服务。 该项目的成果也有望转移到课堂上，特别是使单个原子和分子及其相互作用可视化的图像。 此外，学生，包括K-12，在参观实验室时经常对可视化感到兴奋。 这些活动将通过周六的实地考察和高中生的特别暑期项目得到加强。

Non-Technical AbstractThe primary objective of the proposed research lies in the study of chemistry at the atomic scale by the use of homemade scanning tunneling microscope (STM). By probing individual atoms and molecules, their interactions with the environment and assembly into more complex nanostructures, it should be possible to gain new knowledge on chemical bonding, structure, and reactivity. This knowledge would enable better control of chemistry, allowing the synthesis of new molecules, the assembly of previously unknown systems, and the realization of technological innovations. Since the experiments probe chemistry at the quantum mechanical level, some of the results should serve as physical realization of problems and concepts that are currently taught in modern physics and chemistry courses. Equally important is the visualization provided by the imaging capabilities of the STM. Atoms, molecules, and their assemblies previously only imagined using words and pictures can now be imaged and visualized. Such images provide powerful impressions on the general public, and make effective outreach to K-12 and university students. The subject of the proposed research on individual atoms and molecules is an important one since they form the building blocks of everything around us. Furthermore, seeing individual atoms and molecules and their interactions takes the public a step closer to the understanding and appreciation of the new nanotechnology. In summary, this project advances our basic understanding of science and technology as well as serving an effective outreach and education of students and the general public through visualization of what and how every matter comes to be. The project is being co-funded by the Chemistry Division and the Division of Materials Research.Technical Abstract:Two unique, homemade low temperature scanning tunneling microscopes (STM) are used to probe the interior of single molecules and their assemblies. One of the STMs incorporates an RF excitation source and is immersed in a low magnetic field of 700 Gauss and operates at 15 K. The second STM reaches 1 K and is in a magnetic field up to 9 Tesla. These unique STMs enable novel experiments to be carried out, including atomic scale spin properties and magnetism, high resolution spectroscopy, and quantum tunneling. The systems expand over a large range of size, starting from single hydrogen atoms to multi-atom metal-containing organic molecules. By probing the interior of single molecules, it has become possible to understand the their inner machineries, including electron-vibrational coupling, energy and electron transfers, spin structure and coupling, and nuclear motions leading to bond dissociation or formation. Instrumentation development and refinement continue to be an important mission of this project, enabling the realization of cutting-edge research techniques. All aspects of the two STMs are homemade, including the microscope, electronics, and software. The students gain valuable laboratory skills and experience in solving problems. This knowledge serves them well in their future careers by providing them with the capabilities in entering new fields and tackling problems that may be remotely connected with their university training. Results from the project are also expected to be transferred to the classroom, particularly the images that enable the visualization of individual atoms and molecules as well as their interactions. In addition, students, including K-12, are often excited by the visualization during visits to the laboratory. These activities will be enhanced through field trips on Saturdays and special summer programs for high school students.