RUI: Investigations of One- and Two-Color Laser-Assisted Electron Scattering

RUI：一色和二色激光辅助电子散射的研究

• 批准号: 1708108
• 负责人: Bruno deHarak
• 金额: $ 15万
• 依托单位: Illinois Wesleyan University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708108&HistoricalAwards=false
• 关键词: RUI; Investigations; Two; Color; Laser

Knowing the microscopic structures of molecules and materials is key to understanding their physical and chemical properties and therefore their basic functions and technological applications. However, in addition to measuring structures, which is widely carried out using electron scattering, physicists seek to understand the interactions that occur between electrons and molecules during the scattering process itself. This knowledge can then be used to develop more sensitive techniques for determining structures, for example, while a molecule is undergoing a structural change. Knowledge gained through these studies can also influence applications of electron-atom-laser interactions, which include the generation of short pulses of extreme ultraviolet light that are used to measure ultrafast physical and chemical processes. The goal of this research is to understand electron-atom scattering in the presence of an intense laser field, in particular, how electrons in atoms and molecules respond to intense fields. Without the laser field, the simplest thing that can happen is that the electron and the atom do not exchange energy and continue on their way after the collision with the same energies that they had before the collision, possibly changing only their direction. Addition of light from a laser can cause such ?elastically? scattered electrons to absorb some number of photons, which increases the energy of the electron, or emit photons, thereby reducing the electron's energy. These are called laser-assisted free-free (LAFF) processes because the electron is free, i.e., not bound to an atom or molecule, both before and after the collision. This work will involve experimental LAFF studies, with the broad aim of increasing our basic understanding of these processes. Particular attention will be paid at looking for interference effects in LAFF experiments that use a two-color (photon energy = 1.17 eV, and 2.34 eV) laser field, and which might be used to control scattering processes. In addition to the advancement of our basic understanding of scattering processes, this work has applications to a variety of fields, both basic and applied. For example, LAFF processes are important for understanding the interiors and atmospheres of stars. Free-free transitions also play a major role in the gas breakdown that occurs in electric discharges, and provide a method for laser heating of a plasma (a gas of ionized atoms). This work will primarily take place at an undergraduate institution, and will directly involve several undergraduate students in research.

了解分子和材料的微观结构是理解其物理和化学性质的关键，因此也是理解其基本功能和技术应用的关键。然而，除了使用电子散射广泛进行的结构测量外，物理学家还试图了解散射过程本身中电子和分子之间发生的相互作用。然后，这些知识可以用于开发更灵敏的技术来确定结构，例如，当分子正在经历结构变化时。通过这些研究获得的知识也可以影响电子-原子-激光相互作用的应用，其中包括产生用于测量超快物理和化学过程的极紫外光短脉冲。本研究的目标是了解强激光场存在下的电子-原子散射，特别是原子和分子中的电子如何响应强场。 如果没有激光场，最简单的情况就是电子和原子不交换能量，在碰撞后继续以碰撞前相同的能量继续前进，可能只是改变了它们的方向。激光的光会导致这样的结果吗？弹性？散射的电子吸收一定数量的光子，这增加了电子的能量，或者发射光子，从而降低了电子的能量。这些被称为激光辅助自由-自由（LAFF）过程，因为电子是自由的，即，在碰撞之前和之后都不与原子或分子结合。这项工作将涉及实验LAFF研究，广泛的目的是增加我们对这些过程的基本理解。特别注意将支付在LAFF实验中使用的双色（光子能量= 1.17 eV，和2.34 eV）激光场，并可能被用来控制散射过程中的干扰效应。 除了我们对散射过程的基本理解的进步之外，这项工作还应用于各种领域，包括基础和应用。例如，LAFF过程对于理解恒星的内部和大气层非常重要。自由-自由跃迁在放电中发生的气体击穿中也起着重要作用，并提供了一种激光加热等离子体（电离原子的气体）的方法。这项工作将主要发生在一个本科院校，并将直接涉及研究的几个本科生。

项目成果

Free–free experiments: the search for dressed atom effects

免费——免费实验：寻找修饰原子效应

• DOI: 10.1088/1361-6455/aac31b
• 发表时间: 2018
• 期刊: Molecular and Optical Physics
• 作者: Martin, N L;Weaver, C M;Kim, B N;deHarak, B A
• 通讯作者: deHarak, B A

Angular distribution of electrons elastically scattered from Ar in the presence of a 1.17 eV laser field

存在 1.17 eV 激光场时从 Ar 弹性散射的电子角分布

• DOI: 10.1103/physreva.99.032708
• 发表时间: 2019
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Martin, N. L. S.;Weaver, C. M.;Kim, B. N.;deHarak, B. A.
• 通讯作者: deHarak, B. A.

Observation of dynamic Stark resonances in strong-field excitation

• DOI: 10.1103/physreva.101.053402
• 发表时间: 2019-12
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: D. Chetty;R. Glover;B. deHarak;X. Tong;Han Xu;T. Pauly;Noah H. Smith;K. Hamilton;K. Bartschat;J. Ziegel;N. Douguet;A. Luiten;P. Light;I. Litvinyuk;R. Sang