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Intermetallic and Extraordinary Bonds of Beryllium and the Alkaline Earth Metals

铍和碱土金属的金属间键和非常键

基本信息

批准号：
1900555
负责人：
Michael Heaven
金额：
$ 23.4万
依托单位：
Emory University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-01 至 2021-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1900555&HistoricalAwards=false
关键词：
Intermetallic Extraordinary Bonds Beryllium Alkaline

项目摘要

In this award, funded by the Chemical Structure, Dynamics and Mechanisms-A Program of the Chemistry Division, Professor Michael C. Heaven and his research group at Emory University are investigating the unusual bonding mechanisms of the element beryllium (Be). A common type of chemical bond is called a covalent single bond, where two electrons are shared by two atoms, each atom of the pair typically contributing one electron to the bond. Beryllium atoms are unusual in that they often form what are called dative covalent bonds, where both bonding electrons are provided by the other atom. The Heaven research group is using specialized lasers and mass spectrometers to characterize the structure and properties of small molecules containing Be and other metal atoms (e.g., BeLi, LiBeLi, Li4Be2, where "Li" is a lithium atom). The chemistry of beryllium is underexplored due to its toxicity. However, Be and its compounds exhibit unique and useful properties. For example, beryllium alloys are used as lightweight structural materials due to their exceptional strength to weight ratios. The remarkable durability of the metal is reflected by the fact that it is used as a plasma facing material in fusion reactors. This research project is providing new insights into chemical bonding in general, as well as data that can be used to test new theories on bonding and help in the prediction of the properties of new Be compounds for new technological applications. The graduate students engaged in this project are gaining experience in both experimental and theoretical chemistry. Undergraduate students from the Atlanta University Center Consortium (AUCC) institutions are also involved in the project. This successful collaboration with AUCC institutions provides research opportunities for undergraduate students from Historically Black Colleges and Universities (HBCUs). Undergraduate researchers are not only receiving technical training related to Be chemistry, but also developing soft skills, such as networking, manuscript preparation and oral presentation of research results.At present, the experimental data needed to evaluate quantum chemical models for beryllium are lacking. This validation is needed to establish confidence in the computational methods used to identify compounds with valuable physical and chemical properties. Experimental studies of prototypical beryllium compounds are the primary objectives of this research. Spectroscopic techniques, including laser-induced fluorescence (LIF) and pulsed-field ionization-zero electron kinetic energy (PFI-ZEKE) are being applied to gas phase molecules and ions to obtain structural and thermodynamic properties. The species being examined, including LiBe (and ions LiBe(+), LiBe(-)) and LiBeLi are chosen because they have been the subjects of high-level theoretical investigations in the Heaven laboratory and by others. In addition to the experimental spectroscopic work, this project employs computational studies that utilize complete active space self-consistent field (CASSCF) and multi-reference configuration interaction (MRCI). The research provides the graduate and undergraduate students, and post-doctoral associates involved with a rich experience in advanced experimental and theoretical methods.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.

在这项由化学系化学结构、动力学和机制计划资助的奖项中，埃默里大学的Michael C.Heaven教授和他的研究小组正在研究Be元素的不寻常的成键机制。一种常见的化学键类型称为共价单键，其中两个电子由两个原子共享，该对中的每个原子通常为键提供一个电子。铍原子的不同寻常之处在于，它们经常形成所谓的配位共价键，其中两个成键电子都由另一个原子提供。天堂研究小组正在使用专门的激光和质谱仪来表征含有Be和其他金属原子(例如，Beli，LiBeLi，Li4Be2，其中Li是锂原子)的小分子的结构和性质。由于铍的毒性，人们对其化学研究还不够深入。然而，Be及其化合物表现出独特而有用的性质。例如，铍合金因其优异的强度重量比而被用作轻质结构材料。这种金属的非凡耐用性反映在它被用作聚变反应堆中的面向等离子体的材料的事实上。这项研究项目提供了对一般化学键的新见解，以及可用于测试新的成键理论和帮助预测新的Be化合物在新技术应用中的性质的数据。从事这一项目的研究生正在获得实验和理论化学方面的经验。来自亚特兰大大学中心联盟(AUCC)机构的本科生也参与了这个项目。这次与AUCC机构的成功合作为历史上的黑人学院和大学(HBCU)的本科生提供了研究机会。本科生研究人员不仅接受与Be化学相关的技术培训，还在发展软技能，如网络、稿件准备和研究成果的口头陈述。目前，缺乏评估铍量子化学模型所需的实验数据。这一验证是建立对用于识别具有有价值的物理和化学特性的化合物的计算方法的信心所必需的。原型铍化合物的实验研究是本研究的主要目的。光谱技术，包括激光诱导荧光(LIF)和脉冲场电离-零电子动能(PFI-ZEKE)正被应用于气相分子和离子，以获得结构和热力学性质。被研究的物种，包括LIBE(和离子LIBE(+)，LIBE(-))和LiBeLi被选中，因为它们已经成为天堂实验室和其他人高水平理论研究的对象。除了实验光谱工作外，该项目还使用了利用完全活动空间自洽场(CASSCF)和多参考组态相互作用(MRCI)的计算研究。这项研究为研究生和本科生以及博士后合作伙伴提供了先进的实验和理论方法方面的丰富经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。