Calcium: Chemically and Electronically a Transition Metal?

钙：从化学角度和电子角度来说是一种过渡金属？

• 批准号: 2303197
• 负责人: Hrvoje Petek
• 金额: $ 39万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2303197&HistoricalAwards=false
• 关键词: Calcium; Chemically; Electronically; Transition; Metal

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program in the Division of Chemistry, Professor Hrvoje Petek of the University of Pittsburgh is investigating the chemical reactivity and properties of calcium using surface electronic spectroscopy and scanning tunneling microcopy. Calcium metal is very reactive in ambient conditions, so understanding its chemical and physical properties has remained elusive. As a result, Professor Petek and his team will use ultrahigh vacuum methods to prepare calcium films and atomic scale imaging and spectroscopic methods to investigate reactivity under highly controlled conditions. Students engaged in this research will gain exposure to state-of-the-art spectroscopic methods and learn to apply these to fundamental questions at the interface of physical and inorganic chemistry, including, in this case, thinking about the role calcium plays in carbon capture at a single molecule level.Calcium, which has a fully occupied 4s shell, readily transfers an electron to interacting molecules; however, it is unclear whether this process involves the s- or d- orbitals. To elucidate this mechanism, calcene, a structure in which calcium atoms are arranged in a honeycomb structure and appears to involve strong d-orbital character, will be investigated under well-controlled conditions using two-photon photoemission spectroscopy and scanning tunneling microscopy. These two methods are expected to reveal the ensemble averaged and atomic scale occupied and unoccupied electronic structures of well-defined materials, under ultrahigh vacuum to help classify the calcium states as either alkali or transition metal. By exposing the calcium films to small molecules such as carbon dioxide, water, and oxygen; their reactivity and electronic behavior is expected to reveal the electronic character of the bonds that form. If successful, these studies are expected to lead to broader application of the approach to other elements/catalytic systems.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、动力学和机理a （CSDM-A）项目的支持下，匹兹堡大学的Hrvoje Petek教授正在利用表面电子光谱和扫描隧道显微复制技术研究钙的化学反应性和性质。金属钙在环境条件下非常活跃，因此了解其化学和物理性质仍然是难以捉摸的。因此，Petek教授和他的团队将使用超高真空方法制备钙膜，并使用原子尺度成像和光谱方法在高度控制的条件下研究反应性。参与这项研究的学生将接触到最先进的光谱方法，并学习将这些方法应用于物理和无机化学界面的基本问题，包括在这种情况下，思考钙在单分子水平上的碳捕获中的作用。钙的4s壳层被完全占据，很容易将一个电子转移到相互作用的分子中；然而，尚不清楚这个过程是否涉及s-轨道或d-轨道。为了阐明这一机制，钙烯，一种钙原子排列成蜂窝结构的结构，似乎涉及强d轨道特征，将在良好控制的条件下使用双光子光电发射光谱和扫描隧道显微镜进行研究。这两种方法有望揭示明确定义的材料在超高真空下的系综平均和原子尺度上的占据和未占据电子结构，以帮助将钙状态分类为碱或过渡金属。通过将钙膜暴露在二氧化碳、水和氧气等小分子中；它们的反应性和电子行为有望揭示所形成的键的电子特征。如果成功，这些研究预计将导致该方法更广泛地应用于其他元素/催化系统。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。