Electron-Atom Scattering Dynamics

1914年，J. Franck和G.赫兹进行了一项实验，发挥了至关重要的作用，建立现代原子理论。 他们在1925年获得了诺贝尔奖，这项实验研究了电子与汞原子的碰撞。 自从第一次研究以来，电子-原子（分子）散射领域在复杂性和重要性方面都有了巨大的发展。 这一领域的重要性日益增加，因为发现了许多不同的自然现象，以及涉及电子-原子（分子）碰撞的技术过程。 相关现象的巨大范围包括行星高层大气中发生的过程、聚变等离子体中发生的过程、应用于制造半导体器件的技术以及活组织中发生的辐射损伤。 要完全理解这些现象和进一步发展相关的技术过程，就需要对感兴趣的原子（分子）的电子散射进行定量表征，并为在实验室中继续研究这一领域提供动力。 在这项拨款申请中，资金被要求支持一个正在进行的计划，在电子与原子和分子碰撞的实验研究。 我们的主要兴趣是目前集中在碰撞现象涉及激发态原子的目标，这在很大程度上仍然是未开发的领域，但在等离子体研究中具有很大的实用价值。 我们的方法涉及到预激发的原子目标的激光辐射和测量的碰撞过程，涉及这个预激发的目标。 这些技术正在迅速发展，作为碰撞研究中的重要工具，激光可以用作控制和探测碰撞反应的手段。 在我们的情况下，除了提供一个有效的机制，用于生产高浓度的激发散射目标，激光辐射的使用使我们能够准备在一个“纯量子态”的激发原子。 因此，我们可以阐明碰撞过程的物理学，并在最基本的水平上与新的理论模型建立联系。

In 1914, J. Franck and G. Hertz performed an experiment which played a vital role in establishing modern atomic theory.  That experiment, for which they won the Nobel Prize in 1925, examined the collisions of electrons with mercury atoms.  The field of electron-atom (molecule) scattering has grown enormously, both in sophistication and importance, since that first study.  The growing importance of this field arises from the discovery of numerous and diverse natural phenomena, as well as technological processes, which involve electron-atom (molecule) collisions.  The immense spectrum of relevant phenomena includes processes occurring in the upper atmospheres of the planets, processes occurring in fusion plasmas, techniques applied to the fabrication of semiconductor devices and occurrence of radiation damage in living tissue.  Complete understanding of these phenomena and the further development of the relevant technological processes requires the quantitative characterization of electron scattering from the atoms (molecules) of interest and supplies the motivation for the continued study of this field in the laboratory.   In this grant application, funding is being requested to support an ongoing program in the experimental investigation of electron collisions with atoms and molecules.  Our primary interest is currently focused on collision phenomena involving excited-state atomic targets, a field which remains largely undeveloped but is of great practical value in plasma studies.  Our method involves pre-excitation of the atomic target by laser radiation and the measurement of collision processes involving this pre-excited target.  Such techniques are developing rapidly as important tools in collision studies where lasers can be utilized as a means to control and probe collision reactions.  In our case, in addition to providing an efficient mechanism for the production of high concentrations of excited scattering targets, the use of laser radiation allows us to prepare the excited atom in a "pure quantum state".  We can thereby elucidate the physics of the collision process and make the connection with new theoretical models at the most fundamental level possible.