Electron-Atom Scattering Dynamics

1914年，J·弗兰克和G·赫兹进行了一项实验，在建立现代原子理论方面发挥了至关重要的作用。在那次实验中，他们在1925年获得了诺贝尔奖，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。这个领域的重要性越来越重要，因为发现了无数和不同的自然现象，以及涉及电子-原子(分子)碰撞的技术过程。相关现象的广谱包括发生在行星上层大气中的过程，聚变等离子体中发生的过程、应用于半导体器件制造的技术以及活组织中发生的辐射损伤。完全了解这些现象和进一步发展相关技术过程需要对感兴趣的原子(分子)的电子散射进行定量表征，并为实验室继续研究这一领域提供动力。在这项拨款申请中，正在申请资金以支持正在进行的电子与原子和分子碰撞的实验研究计划。我们目前的主要兴趣集中在涉及激发态原子目标的碰撞现象上，这一领域在等离子体研究中仍有很大的实用价值。我们的方法涉及激光辐射对原子目标的预激发，以及涉及这种预激发目标的碰撞过程的测量。这些技术作为碰撞研究的重要工具正在迅速发展，激光可以用作控制和探测碰撞反应的手段。就我们的情况而言，除了为产生高浓度的受激发散射靶提供了一种有效的机制外，激光辐射的使用还使我们能够将受激发的原子准备在一个“纯量子态”中。因此，我们可以阐明碰撞过程的物理过程，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.