RUI: Negative Ion Photodetachment Spectroscopy

非技术描述：激光和其他光源将被用来测量负离子的性质，负离子是指有一个额外电子的原子和分子。高精度测量额外的电子被束缚的紧密程度，对于模拟化学反应和等离子体相互作用非常有用，在制造用于计算机和其他电子设备的半导体等实际应用中也很有用。对负离子的详细研究将产生对“动态多体相互作用”的见解，这对于理解粒子集合的行为如何不同于人们通过孤立地研究单个粒子所获得的知识所期望的行为是至关重要的。这些相互作用是物理、化学和材料科学（包括纳米技术）广泛领域中感兴趣的普遍现象。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劳伦斯伯克利国家实验室的实验，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。技术描述：本项目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。为了确定电子亲和和能级，将测量几种镧系和III族负离子（镓和可能的铊）的基态和上态光脱离阈值。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，包括存在于铈和镧负离子中的束缚电偶极子跃迁。第二系列的互补实验将在先进光源同步加速器上使用高能（12-1000 eV）光子，研究n个碳原子（O-, H-, C_n-）和其他原子和分子物种的氧、氢和碳链的负离子的内壳光分离。这些实验继续了pi对外层电子对分离的内层电子波函数的影响的研究。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。

Non-technical description:Lasers and other light sources will be used to measure the properties of negative ions, which are atoms and molecules that have an extra electron. High-precision measurements of how tightly the extra electron is bound will be useful for modeling chemical reactions and plasma interactions for such practical applications as the manufacturing of semiconductors for computers and other electronic devices. The detailed studies of negative ions will yield insights into "dynamical many-body interactions" which are central to understanding how collections of particles behave differently from what one would expect from the knowledge gained by studying single particles in isolation. These interactions are 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 Lawrence Berkeley National Laboratory, providing important research experiences for young scientists including technical training in electronics, computers, lasers, and optics. Technical description: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 and upper state photodetachment thresholds of several lanthanide and Group III negative ions (gallium and possibly thallium) will be measured in order to determine the electron affinities and energy levels. 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 exist in the negative ions of cerium and lanthanum. The second series of complementary experiments will investigate inner-shell photodetachment from the negative ions of oxygen, hydrogen, and carbon chains of n numbers of carbon atoms (O-, H-, C_n-) and other atomic and molecular species using high energy (12-1000 eV) photons at the Advanced Light Source synchrotron. These experiments continue the PIs' investigations into 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.