Studies of Nanometer Scale Metal Cluster Dissociation in the Gas Phase

明尼苏达大学双城分校的Christopher Hogan，Steven Girshick和Donald Truhlar教授获得了大分子，超分子和纳米化学计划的奖项，以更好地了解金属簇的形成和生长。该团队正在通过实验和计算相结合的方法研究气相中纳米尺度簇（从6个原子到1000个原子）的性质。具体地说，使用串联微分迁移率分析实验监测金属团簇Mn-Mn-1 + M（其中M是金属，n是金属团簇中的原子数）的解离。这些实验是有史以来第一次测量单原子蒸发气相中性，阳离子和阴离子金属簇在大气压下。同时，金属簇的解离速率推断从分子动力学轨迹模拟允许直接比较实验测量和计算预测。在测量和计算中特别感兴趣的是识别异常幻数和反幻数簇，它们分别是异常稳定的或不稳定的。这些幻数团簇的存在极大地改变了气相金属团簇的成核速率。研究小组从金属簇的测量和计算解离速率推断簇形成和生长的速率，从而能够将簇生长速率预测与新设计的湍流混合金属簇生长反应器中的实验测量进行比较。这些实验和模拟阐明了金属团簇的行为，从而为未来设计具有纳米尺度特征的多组分金属材料的合成系统提供了基础。这一研究领域在环境和材料科学中有技术应用，例如。例如，在一个实施例中，垃圾焚烧和燃煤废气。该项目是跨学科的性质，物理化学和机械工程学科的桥梁。它的独特之处在于它结合了新开发的实验技术和尖端的分子模拟，其中重叠迄今为止很少。此外，这些研究是将分子尺度上的材料性质与散装材料性质联系起来的重要努力的一部分。这些研究的其他更广泛的影响包括参与该项目的研究生和博士后研究人员的跨学科教育，包括从化学家和工程师的角度开发新的跨学科课程，重点关注纳米尺度簇的性质。

Professors Christopher Hogan, Steven Girshick, and Donald Truhlar of the University of Minnesota-Twin Cities are receiving an award from the Macromolecular, Supramolecular and Nanochemistry Program to better understand metal cluster formation and growth. The team is examining the properties of nanometer scale clusters (from as small as 6 atoms up to 1000 atoms) in the gas-phase by a combined experimental and computational approach. Specifically, the dissociation of metal clusters, Mn -- Mn-1 + M (where M is a metal and n is the number of atoms in a metal cluster) is monitored experimentally using tandem differential mobility analysis. These experiments are the first ever measurements of single atom evaporation from gas phase neutral, cationic, and anionic metal clusters at atmospheric pressure. Simultaneously, the dissociation rates of metal clusters are inferred from molecular dynamics trajectory simulations allowing for direct comparison of experimental measurements and computational predictions. Of particular interest in measurements and computations is the identification of anomalous magic number and anti-magic number clusters, which are either anomalously stable or unstable, respectively. The existence of these magic number clusters vastly alters the rate of nucleation for gas phase metal clusters. The team of researchers infers the rate of cluster formation and growth from the measured and computed rates of dissociation for metal clusters, enabling comparison of cluster growth rate predictions to experimental measurements in a newly designed turbulent mixing metal cluster growth reactor. These experiments and simulations elucidate the behavior of metallic clusters, thus providing the basis for the design of future synthesis systems for multi component metallic materials with nanoscale features. This area of research has technological applications in environmental and materials sciences, e. g., waste incineration and coal burning exhausts. This project is interdisciplinary in nature, bridging the disciplines of physical chemistry and mechanical engineering. It is unique in that it incorporates both newly developed experimental techniques and cutting-edge molecular simulations, where overlap has thus far been sparse. Moreover, these studies are part of a vital effort to link the properties of materials at the molecular scale to properties of bulk materials. Additional broader impacts of these studies include the interdisciplinary education of graduate students and postdoctoral researchers involved in the project, including the development of new interdisciplinary courses focusing on the properties of nanometer scale clusters from both the chemist's and engineer's perspective.