Electron and Positronium Collisions with Molecules

低能电子及其反粒子正电子在许多基础和应用领域中起着至关重要的作用。电子可以诱导与介质老化、表面工程、辐射损伤、癌症治疗和大气物理有关的特定化学反应。涉及正电子和含有正电子的原子的碰撞在正在进行的物质和反物质基本性质的研究中起着重要作用。为什么在我们的宇宙中物质比反物质占主导地位？要回答这个大问题，需要研究最简单的反物质原子——反氢。反氢原子的产生可以通过反质子与正电子原子碰撞来完成，每个正电子原子都含有一个电子和一个正电子。这些过程目前正在瑞士的欧洲核子研究中心实验室进行研究，该实验室提供了强大的反质子源。本项目将通过提供基本碰撞理论的基础，并通过将现有碰撞理论扩展到未知领域，为这些努力作出贡献。获奖研究将在化学控制、放射生物学、大气科学和反物质基本性质研究等领域产生影响。这项研究涉及跨学科的努力以及与其他物理和化学领域的科学家的国际合作。对研究生的监督促进了他们在不同物理领域的训练。该项目涉及电子分子和正电子分子碰撞过程的研究。这些研究补充了正电子与质子和反质子碰撞的更基本过程的理论研究。研究重点是多原子分子的解离电子附着理论的发展，这一过程导致分子中的键断裂并将其解离成中性和带负电的碎片。利用有效势计算正电子与双原子分子的碰撞，重点讨论共振散射。新的量子力学方法用于正电子-质子/反质子碰撞的理论研究，并与以前的经典模拟结果进行了比较。这些研究活动促进了电子和正电子与分子和质子/反质子相互作用的理论。首先，他们开发了新的形式，然后将其应用于电子和正电子与各种目标的碰撞。其次，它们产生了新的数据，促进了对这些过程的理解，特别是解离电子附着过程和正电子-分子弹性和非弹性碰撞。第三，他们确定了过去用于处理正电子-质子/反质子碰撞的经典方法的有效性范围。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Low-energy electrons and their antiparticles, positrons, play a critical role in a large number of fundamental and applied fields. Electrons can induce specific chemical reactions which are relevant to dielectric aging, surface engineering, radiation damage, cancer therapy, and atmospheric physics. Collisions involving positrons and positron-containing atoms play an important role in ongoing investigations of fundamental properties of matter and antimatter. Answers to the big question of why matter dominates over antimatter in our universe require studies of the simplest antimatter atom, antihydrogen. Creation of antihydrogen atoms can be accomplished by colliding antiprotons with positronium atoms, each containing an electron and a positron. These processes are currently investigated at the CERN laboratory in Switzerland, which provides the powerful source of antiprotons. This project will contribute to such efforts by providing a foundation of basic collision theory, and by extending existing collision theory into uncharted domains. The awarded research will have impact in the areas of chemical control, radiobiology, atmospheric science, and in studies of fundamental properties of antimatter. The research involves interdisciplinary efforts and international collaborations with scientists from other fields of physics and chemistry. Supervision of graduate students promotes their training in diverse areas of physics.The project involves studies of electron-molecule and positronium-molecule collision processes. These studies are supplemented by theoretical investigation of more fundamental processes of positronium collisions with protons and antiprotons. The research focus is on development of the theory of the dissociative electron attachment to polyatomic molecules, the process resulting in bond breaking in molecules and dissociating them into neutral and negatively charged fragments. Effective potentials are used for calculation of positronium collisions with diatomic molecules with emphasis on the resonant scattering. New quantum-mechanical methods for theoretical studies of positronium-proton/antiproton collisions are being developed and compared with results of previous classical simulations. The research activities advance the theory of electron and positronium interactions with molecules and protons/antiprotons. First, they develop new formalisms which are then applied to electron and positronium collisions with various targets. Second, they lead to generation of new data which promote understanding of these processes, particularly dissociative electron attachment processes and positronium-molecule elastic and inelastic collisions. Third, they determine the range of validity of classical methods for treatment of positronium-proton/antiproton collisions which were used in the past.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.