RUI: Closing the Gap Between Hot and Cold Collisions--Orientation, Alignment, and Velocity Effects on Associative Ionization of State-selected Atoms in a Single Beam

这个RUI研究项目将测量激发态原子之间的碰撞，目的是研究分子结构和探索碰撞理论。主要目标是弥合传统碰撞研究（在高温下，即在气体细胞的温暖温度下进行）和在超冷圈闭中进行的实验之间的速度差距。实验程序利用窄带宽二极管激光器来选择热铯光束的薄速度分量。在精确控制的速度分量之间的碰撞导致缔合电离，两个被激发的原子通过射出一个电子带走多余的能量形成分子键。窄带宽二极管激光器还可以控制原子的取向和对准，这是碰撞理论中的重要参数。以铯为例，缔合电离提供了一个简单但重要的化学键形成的例子，涉及单电子键。这种简单性使铯的缔合电离成为对碰撞理论的一个很好的检验。除了评估理论和理解亚开尔文环境下的碰撞过程之外，该项目更广泛的影响还包括加强拉斐特学院的研究和教学基础设施，以及培养未来的物理学家，以进入研究生院和工业界就业。通过直接参与这项研究，本科生可以获得实际的动手实验经验。将本项目的各个方面整合到本科实验课程中，为学生提供了接触现代实验室技术的第二途径。

This RUI research project will measure collisions between excited-state atoms with the purpose of studying molecular structure and exploring collision theory. The primary goal is to bridge the velocity gap between traditional collision studies (done at thermal, i.e., warm temperatures in gas cells) and experiments carried out in ultracold traps. The experimental procedure makes use of narrow-bandwidth diode lasers to select thin velocity components of a thermal cesium beam. Collisions between precisely controlled velocity components lead to associative ionization, where two excited atoms form a molecular bond by ejecting an electron to carry off excess energy. The narrow-bandwidth diode lasers also allow control of atomic orientation and alignment, which are important parameters in collision theory. For the case of cesium, associative ionization offers a simple, but important example of chemical bond formation, involving one-electron bonds. This simplicity makes associative ionization of cesium a good test of collision theory. Beyond evaluating theories and understanding collision processes in sub-Kelvin environments, the broader impact of this project includes enhancing the research and teaching infrastructure of Lafayette College and training future physicists destined for graduate school and employment in industry. Undergraduates are provided with practical hands-on laboratory experience by participating directly in this research. The integration of various aspects of this project into the undergraduate laboratory curriculum provides a second avenue through which students are exposed to modern laboratory techniques.