Muons as Sensitive Isotopic H-atom Probes of Quantum Mass Effects in Chemical Reactivity and of the Motion of Muoniated Free Radicals in Nanoparticle Environments.

μ 子作为化学反应中量子质量效应和纳米颗粒环境中 μ 化自由基运动的敏感同位素氢原子探针。

• 批准号: 43731-2012
• 负责人: Fleming, Donald
• 金额: $ 2.55万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=568912
• 关键词: Muons; Sensitive; Isotopic; atom; Probes

The study of chemical reaction rates is central to the whole field of chemistry and in this study it is often the most simple elementary steps in a complex mechanism that are the most important. Chief among these are the reaction rates of the H-atom and its isotopic variants; deuterium (D), with a mass of 2 amu, being the most well known. Isotopes have the same number of electrons but different nuclear masses. Another common hydrogen isotope is tritium (T), with a mass of 3 amu, but being dangerously radioactive, it has seen little use in the study of thermal reaction rates. Thus it has fallen to nuclear science and particularly muon science to extend the isotopic H-atom mass scale. The lightest isotope of the H-atom is Muonium (Mu= u+e-), where `u+' is a positive muon, with a mass only 1/9th that of the proton. Though lacking a "nucleus'' in the conventional sense, the muon mass is still 200 times the electron mass, meaning that Mu and H atoms exhibit the same chemistry, but with very different reaction rates due to their factor of nine difference in mass. This application is concerned with new directions in Mu reactivity from state- selected reactants, using lasers to populate molecular excited states. At the other end of the mass scale is the Muonic He atom (4Heu), where negative muons from the TRIUMF accelerator are captured by a Helium atom, replacing one electron in the process, thereby endowing 4Heu with a mass of 4.1 amu, the heaviest isotope of the H-atom. We are now in a position to compare the reaction rates of Mu and 4Heu over an unprecedented ratio of a factor of 36 in mass, also a key aspect of the present application. A possible practical aspect of our study of Mu reactivity is the formation of ''muoniated radicals'' and in particular their motional effects in important industrial catalysts like Zeolites, for which there is no other technique that can yield the same detailed results. This too is an important aspect of the present application, but extended to other environments, the study of muoniated radicals on Au nanoparticles.

化学反应速率的研究是整个化学领域的核心，在这项研究中， 复杂机械中最简单的基本步骤，也是最重要的步骤。其中最主要 是氢原子及其同位素变体的反应速率;氘（D），质量为2 amu， 最知名的。同位素具有相同的电子数，但核质量不同。另一 常见的氢同位素是氚（T），质量为3 amu，但具有危险的放射性， 在热反应速率的研究中几乎没有什么用处。因此，它已经下降到核科学，特别是 μ介子科学扩展同位素氢原子质量尺度。氢原子最轻的同位素是μ 鎓 (Mu= u+e-），其中“u+”是一个正μ子，质量只有质子的1/9。虽然缺乏A 在传统意义上的“核”，μ子质量仍然是电子质量的200倍，这意味着， Mu和H原子表现出相同的化学性质，但由于它们的因子，反应速率非常不同。 质量相差九倍。本申请涉及从状态到Mu反应性的新方向- 选定的反应物，使用激光填充分子激发态。在质量尺度的另一端 是μ子He原子（4 Heu），其中来自TRIUMF加速器的负μ子被捕获。 氦原子，在这个过程中取代了一个电子，从而赋予4 Heu 4.1 amu的质量， 氢原子最重的同位素。我们现在能够比较Mu和4 Heu的反应速率 超过了前所未有的质量因数36的比率，这也是本申请的关键方面。一 我们研究Mu反应性的一个可能的实际方面是“μ离子化自由基”的形成， 特别是它们在重要的工业催化剂如沸石中的运动效应，这是没有其他方法的。 这是一种可以产生相同详细结果的技术。这也是本申请的一个重要方面， 但扩展到其他环境中，Au纳米颗粒上μ ionated自由基的研究。