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.

在化学结构，动力学和机制-A（CSDM-A）计划的支持下，匹兹堡大学的Hrvoje Petek教授正在研究使用表面电子光谱和扫描隧道微拷贝的钙的化学反应性和钙的性质。钙金属在环境条件下具有反应性，因此了解其化学和物理性质仍然难以捉摸。结果，Petek教授和他的团队将使用超高真空方法来制备钙膜和原子尺度成像和光谱方法，以调查高度控制条件下的反应性。从事这项研究的学生将获得最先进的光谱方法，并学会将这些方法应用于物理和无机化学的界面上的基本问题，包括在这种情况下，考虑钙在碳中的作用在单个分子水平上的作用。但是，目前尚不清楚此过程是否涉及S-或D轨道。为了阐明这种机制，钙质是一种在蜂窝结构中排列钙原子并似乎涉及强D轨道特征的结构，将在良好的控制条件下使用两光子光发射光谱和扫描隧道显微镜进行研究。预计这两种方法将在超高真空下揭示平均和原子量表的平均和原子量表，并占据了定义明确的材料的电子结构，以帮助将钙状态分类为碱性或过渡金属。通过将钙膜暴露于小分子中，例如二氧化碳，水和氧气；他们的反应性和电子行为有望揭示形成的键的电子特征。如果成功的话，这些研究有望导致该方法对其他要素/催化系统的更广泛应用。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响评估标准通过评估来支持的。