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，负离子是具有额外电子的原子和分子。对额外电子结合紧密程度的高精度测量，将有助于为计算机和其他电子设备的半导体制造等实际应用建立化学反应和等离子体相互作用的模型。对负离子的详细研究将使人们深入了解“动态多体相互作用”，这是理解粒子集合的行为如何与人们从孤立研究单个粒子获得的知识所预期的不同的核心。这些相互作用是物理、化学和材料科学(包括纳米技术)中广泛领域感兴趣的普遍现象。该项目将加强丹尼森大学这一本科学院的研究和教学基础设施。学生将参加校园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：该项目在两个相关的系列实验中研究了光子与负离子的相互作用。负离子中的额外电子主要受电子关联效应的约束，因此负离子为关于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测试基础。在第一系列实验中，在丹尼森大学的校园里，使用可调谐红外激光分离外壳电子，研究了复杂的原子负离子。为了确定电子亲和力和能级，将测量几个稀土元素和第三类负离子(镓和可能的铊)的基态和上态光剥离阈值。目前，这些体系的理论预测和实验光电子能谱结果之间存在很大的不一致。教师和学生研究人员还将研究稀土离子中的共振和束缚激发态，包括存在于Ce和La负离子中的束缚电子-偶极跃迁。第二系列补充实验将在先进光源同步加速器上利用高能(12-1000 eV)光子研究氧、氢和n个碳原子(O-、H-、C_n-)和其他原子和分子物种的碳链负离子的内壳层光剥离。这些实验继续了PI对外层电子对分离的内电子波函数的影响的研究。在高度关联的负离子核心的光激发中的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对中性衰变产物的探测将检验描述内壳层光分离的最新理论。

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.