Negative Ion Photoelectron Spectroscopy of Atomic, Molecular and Cluster Anions

原子、分子和团簇阴离子的负离子光电子能谱

• 批准号: 2054308
• 负责人: Kit Bowen
• 金额: $ 60万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2054308&HistoricalAwards=false
• 关键词: Negative; Ion; Photoelectron; Spectroscopy; Atomic

With support from the Chemical Structure, Dynamics, and Mechanisms A (CSDM-A) Program in the Division of Chemistry, Professor Kit Bowen and his group at Johns Hopkins University are studying the negative ions that form when an extra electron is attached to an atom, molecule, or cluster. The addition of electrons to chemical systems can make the unexpected occur, enticing seemingly impossible processes to take place. For example, electrons drive, direct, induce, and initiate an astonishing variety of transformations, including DNA damage, proton transfer, molecular activation, and a vast array of electrochemical reactions. The negative ions that result from electron attachment are also crucial actors in chemical reaction mechanisms, playing key roles in organic chemistry, electrochemistry, and radiation biology. Electron-influenced processes in complex environments are ubiquitous. For these reasons, a microscopic understanding of basic phenomena involving excess electrons is essential. To probe these phenomena, Dr. Bowen and his group use a technique called negative ion photoelectron spectroscopy to measure how tightly electrons are bound to negatively charged atoms, molecules, and clusters. The experiments reveal detailed information about both the ions and their neutral counterparts, while also providing important benchmarks for computational chemistry. Considering the wide-ranging importance of electron-driven processes, the work in Dr. Bowen’s lab has interdisciplinary appeal, with impact ranging across fields as diverse as atmospheric chemistry, catalysis, radiation chemistry and biology, astrochemistry, and mass spectrometry. Dr. Bowen’s work also makes strong contributions to education and human resource development by mentoring graduate students who will become the scientists of tomorrow, by providing undergraduates from Johns Hopkins and other colleges and universities an opportunity to participate in cutting-edge research, and by giving high school, middle school, and elementary school students a glimpse into scientific research. The outreach efforts encourage participation from groups that are underrepresented in science.Dr. Bowen’s research examines electron-induced proton transfer (EIPT) reactions, weakly-bound (diffuse) excess electron states of atoms and molecules, and the properties of transient molecular anions. For example, the research team is exploring the role of EIPT in cluster anions, where they expect the internal interactions to be governed by the excess electron. EIPT is a wide-spread, perhaps even ubiquitous electron-assisted process. The team is also examining the relationship between EIPT in ground-state molecular anions and the process of excited-state intra-molecular proton transfer (ESIPT) in neutral molecules. Dr. Bowen’s research on weakly-bound (diffuse) excess electron states examines some of the most subtle interactions in chemistry; those between electrons and atoms or molecules. In this area, the research team is studying the formation and characterization of polarizability-bound electrons in xenon atomic cluster anions and in ground state anions of buckminsterfullerene; quadrupole-bound electrons in electronically metastable atomic metal anions; and multiple Rydberg electrons in metal-ammonia cluster anions. Although the electrons are weakly bound in each of these cases, they represent steps on a staircase of progressively stronger interactions. Finally, the research team is studying transient molecular anions using a unique approach, developed by Dr. Bowen, that combines Rydberg electron transfer with anion photoelectron spectroscopy (RET-aPES). The research team uses the RET-aPES technique to form and characterize valence anions of nucleobase molecules, the Criegee intermediate, and the hydrogen iodide molecule. They are also using RET-aPES to explore the barely studied, yet fundamentally important process of Penning electron detachment. These studies foster a deeper understanding of the earliest stages of electron damage to DNA, the electrophilic properties of important atmospheric intermediates, the unexpected stability of HI anion, and collisional anion destruction processes in energetic gaseous environments, such as flames and solar atmospheres. The outcomes from this broad research project are expected to have widespread impact across many fields of science. Additionally, the project provides advanced training opportunities for graduate and undergraduate research students, while also engaging K-12 students through Dr. Bowen's outreach activities.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.

在化学系化学结构，动力学和机制A（CSDM-A）计划的支持下，约翰霍普金斯大学的Kit Bowen教授和他的团队正在研究当一个额外的电子连接到原子，分子或簇时形成的负离子。在化学系统中添加电子可以使意想不到的事情发生，诱使看似不可能的过程发生。例如，电子驱动、引导、诱导和引发各种各样的转化，包括DNA损伤、质子转移、分子活化和大量的电化学反应。由电子附着产生的负离子也是化学反应机制中的关键因素，在有机化学、电化学和辐射生物学中起着关键作用。复杂环境中的电子影响过程是普遍存在的。由于这些原因，对涉及过量电子的基本现象的微观理解是必不可少的。为了探索这些现象，Bowen博士和他的团队使用一种称为负离子光电子能谱的技术来测量电子与带负电荷的原子、分子和团簇的结合程度。这些实验揭示了离子及其中性对应物的详细信息，同时也为计算化学提供了重要的基准。考虑到电子驱动过程的广泛重要性，Bowen博士实验室的工作具有跨学科的吸引力，其影响范围涵盖大气化学，催化，辐射化学和生物学，天体化学和质谱等领域。Bowen博士的工作也为教育和人力资源开发做出了巨大贡献，指导研究生谁将成为明天的科学家，通过提供来自约翰霍普金斯和其他学院和大学的本科生参与前沿研究的机会，并通过让高中，初中和小学的学生一瞥科学研究。Bowen博士的研究考察了电子诱导质子转移（EIPT）反应、原子和分子的弱束缚（扩散）过量电子态以及瞬态分子阴离子的性质。例如，研究小组正在探索EIPT在簇阴离子中的作用，他们预计内部相互作用将由多余的电子控制。EIPT是一种广泛存在的，甚至可能是无处不在的电子辅助过程。该团队还研究了基态分子阴离子中的EIPT与中性分子中激发态分子内质子转移（ESIPT）过程之间的关系。Bowen博士对弱束缚（扩散）过量电子态的研究考察了化学中一些最微妙的相互作用;电子与原子或分子之间的相互作用。在这一领域，研究小组正在研究氙原子团簇阴离子和巴克敏斯特富勒烯基态阴离子中极化率束缚电子的形成和表征;电子亚稳态原子金属阴离子中的四极束缚电子;以及金属氨团簇阴离子中的多个里德伯电子。虽然在每一种情况下，电子的束缚都很弱，但它们代表了一个逐步增强相互作用的阶梯。最后，研究小组正在使用Bowen博士开发的独特方法研究瞬态分子阴离子，该方法将Rydberg电子转移与阴离子光电子能谱（RET-aPES）相结合。研究小组使用RET-aPES技术来形成和表征核碱基分子、Criegee中间体和碘化氢分子的价阴离子。他们还使用RET-aPES来探索几乎没有研究过的，但从根本上重要的潘宁电子分离过程。这些研究促进了对DNA电子损伤的最早阶段、重要大气中间体的亲电性质、HI阴离子的意外稳定性以及高能气体环境（如火焰和太阳大气）中碰撞阴离子破坏过程的更深入理解。这一广泛研究项目的成果预计将对许多科学领域产生广泛影响。此外，该项目还为研究生和本科生提供高级培训机会，同时通过Bowen博士的推广活动吸引K-12学生。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Photoelectron Spectroscopic and Computational Study of the Deprotonated Gallic Acid and Propyl Gallate Anions

去质子化没食子酸和没食子酸丙酯阴离子的光电子能谱和计算研究

• DOI: 10.1021/jasms.2c00017
• 发表时间: 2022
• 期刊: Journal of the American Society for Mass Spectrometry
• 影响因子: 3.2
• 作者: Zhu, Zhaoguo;Marshall, Mary;Harris, Rachel;Collins, Evan;Bowen, Kit H.
• 通讯作者: Bowen, Kit H.

Photoelectron Spectroscopic Study of Ascorbate and Deprotonated Ascorbate Anions Using an Electrospray Ion Source and a Cryogenically Cooled Ion Trap

使用电喷雾离子源和低温冷却离子阱对抗坏血酸和去质子化抗坏血酸阴离子进行光电子能谱研究

• DOI: 10.1021/acs.jpca.1c06540
• 发表时间: 2021
• 期刊: The Journal of Physical Chemistry A
• 作者: Marshall, Mary;Zhu, Zhaoguo;Harris, Rachel;Collins, Evan;Bowen, Kit H.
• 通讯作者: Bowen, Kit H.