RUI: Valence and Inner-shell Negative Ion Photodetachment Spectroscopy

本课题在两个相关的系列实验中研究光子与负离子的相互作用。负离子中的多余电子主要由电子相关效应束缚，因此负离子为有关这些多体相互作用的最先进的原子物理计算提供了肥沃的试验场。在第一个系列的实验中，在丹尼森大学的校园里，使用可调谐的红外激光来分离外层电子，研究复杂的原子负离子。为了确定原子的电子亲和力，将测量几种镧系和III族负离子的基态光剥离阈值。目前，这些系统的理论预测和实验光电子能谱结果之间存在很大的分歧。教师和学生研究人员还将研究镧系离子的共振和束缚激发态，包括似乎存在于Ce和La负离子中的束缚电偶极子跃迁。第二个系列的补充实验将在劳伦斯伯克利国家实验室的先进光源（ALS）中使用高能光子研究氧、C60和其他原子和分子物种的负离子的内壳光分离。这些实验继续了pi的一系列研究，以调查外层电子对分离的内层电子波函数的影响。在负离子高度相关核心的光激发下，动态多电子相互作用继续挑战着对原子结构的基本理解。对重负离子的研究和中性衰变产物的检测将检验描述内壳光剥离的最新理论。该项目的更广泛影响包括对原子性质数据库的贡献，与其他科学领域的联系，以及对本科生的教育。在这个项目中测量的高精度电子亲和将有助于模拟化学反应和等离子体相互作用，如半导体加工等实际应用。负离子的详细研究将产生对动态多体相互作用的见解，这是物理、化学和材料科学（包括纳米技术）广泛领域感兴趣的普遍现象。该项目将加强丹尼森大学这所本科学院的研究和教学基础设施。学生们将参加校内和ALS实验室的实验，为年轻科学家提供重要的研究经验，包括电子、计算机、激光和光学方面的技术培训。此外，pi和我们的许多本科生也积极参与师生合作的公共科学推广项目，每年向数百人展示物理和天文学课程。

This project studies the interactions of photons with negative ions in two related series of experiments. The extra electron in a negative ion is bound predominantly by electron correlation effects and therefore negative ions provide a fertile testing ground for state-of-the-art atomic physics calculations regarding these multi-body interactions. In the first series of experiments, complex atomic negative ions are investigated on-campus at Denison University using tunable infrared laser light to detach outer-shell electrons. The ground state photodetachment thresholds of several lanthanide and Group III negative ions will be measured in order to determine the atomic electron affinities. There is currently strong disagreement between theoretical predictions and experimental photoelectron spectroscopy results for these systems. The faculty and student researchers will also investigate resonances and bound excited states in lanthanide ions including bound-bound electric-dipole transitions that appear to exist in the negative ions of Ce and La. The second series of complementary experiments will investigate inner-shell photodetachment from the negative ions of oxygen, C60 and other atomic and molecular species using high energy photons at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. These experiments continue a series of studies by the PIs to investigate the effects of the outer-shell electrons on the detaching inner electron's wavefunction. The dynamic multi-electron interactions in the photoexcitation of the highly correlated cores of negative ions continue to challenge the fundamental understanding of atomic structure. Investigations into heavy negative ions and detection of the neutral decay products will test the latest theories describing inner-shell photodetachment.The broader impacts of the program include contributions to the database of atomic properties, connections to other scientific fields, and the education of undergraduate students. The high-precision electron affinities measured in this project will be useful for modeling of chemical reactions and plasma interactions for such practical applications as semiconductor processing. The detailed studies of negative ions will yield insights into dynamical many-body interaction, which is a general phenomenon of interest for a broad range of fields in physics, chemistry, and materials science, including nanotechnology. The project will enhance the research and teaching infrastructure of Denison University, an undergraduate college. Students will participate in the experiments both on-campus and at the ALS, providing important research experiences for young scientists including technical training in electronics, computers, lasers, and optics. Additionally, both PIs and many of our Undergraduate students are also heavily involved with student-faculty collaborative public science outreach projects that present Physics and Astronomy programs to hundreds of people each year.