Metal Clusters, Metal Nanostructures, Semiconductor Nanocrystals, Single-Ion Magnets

我的研究项目旨在了解和优化金属团簇的催化性能，金属纳米结构和半导体纳米晶体的光电性能，以及掺杂金团簇单离子磁体的操作性能。I)如何优化金属团簇对乙醇氧化的催化性能？乙醇是可再生的、可生物降解的、富含氢气的，可以被氧化来合成一系列有价值的化学品。我们考察了无载体铸币金属簇合物在零开尔文时催化乙醇氧化的第一步的能力。我们发现铜团簇比银或金催化剂更好，阴离子团簇比中性团簇更好，单M原子比M2、M3和M4更好。这些结果将指导我们未来对有限温度下的负载型金属团簇的研究。Ii)如何优化金属纳米结构和半导体纳米晶体的光电性能？对于金属纳米结构，我们将重点关注金，因为它相对不活跃，可以采用许多(局部)稳定的几何结构。我们将重点放在金棒结构上，因为它们可以用作纳米结构设备的电连接器。半导体纳米晶被用于光伏设备。当一个光子被吸收时，就会形成电子-空穴对，并产生电流。它们也用于发生相反过程的显示设备中。由于量子限制，越小的纳米晶体具有更大的带隙，这就更好地利用了更高能量的光子。在实验条件下，这些物种通常是富镉的(且带正电荷)，必须用带负电荷的X型配体如Cd16Se10Cl12和Cd59Se50(CH3COO)18钝化。在实验研究的激励下，我们将考察掺入银原子的小尺寸CdSe纳米晶对电荷迁移率的影响。此外，我们还将研究掺入高自旋原子如Mn、Fe或Co的CdSe纳米晶的磁性。III)如何优化新型单离子磁体的磁性？单分子磁体(SMM)在量子信息处理设备中具有作为量子比特(Qbit)的潜力。SMM通常有6到12个高自旋原子通过氧或氮桥原子相互连接。我们的主要目标是深入了解被称为单离子磁体(SIM)的SMM的一个子集，它通常由一个受配体保护的高自旋原子组成，该原子被捕获在具有固定SIM-SIM距离的晶格中。如果金原子团簇中掺杂了高自旋原子，如Mn、Fe、Co，则由于Au的电负性较大，高自旋原子将带有正电荷。因此，这些物种是一种可以排列在具有最佳SIM卡-SIM卡距离的表面上的新型“自由站立”SIM卡。这可能会产生具有独特功能的量子比特。

My research program seeks to understand and optimize the catalytic properties of metal clusters, the optoelectronic properties of the metal nanostructures and semiconductor nanocrystals, and the operational properties of doped gold cluster single-ion magnets. i) How can we optimize the catalytic properties of metal clusters for ethanol oxidation? Ethanol is renewable, biodegradable, hydrogen rich and can be oxidized to synthesize a wide range of valuable chemicals. We examined the ability of unsupported coinage metal clusters to catalyze the first step of ethanol oxidation at zero Kelvin. We found that copper clusters were better catalysts than silver or gold catalysts and that anionic clusters are better than neutral clusters, and that single M atoms are better catalysts than M2, M3, and M4. These results will guide our future studies of supported metal clusters at finite temperature. ii) How can we optimize the optoelectronic properties of metal nanostructures and semiconductor nanocrystals? For metal nanostructures we will focus on gold since it is relatively unreactive and can adopt many (locally) stable geometries. Our focus is on gold rod structures because they could be used as electrical connectors in nanostructured devices. Semiconductor nanocrystals are used in photovoltaic devices. Upon absorption of a photon, an electron-hole pair is formed and an electrical current can be generated. They are also used in display devices in which the reverse process takes place. Due to quantum confinement, a smaller nanocrystal has a larger band gap, which makes better use of higher energy photons. Under experimental conditions these species are typically cadmium rich (and positively charged) and must be passivated using negatively charged X-type ligands e.g. Cd16Se10Cl12 and Cd59Se50(CH3COO)18. Motivated by experimental studies, we will examine the effect on charge mobility of doping small CdSe nanocrystals with silver atoms. Also, we will examine the magnetic properties of CdSe nanocrystals doped with a high-spin atom such as Mn, Fe, or Co. iii) How can we optimize the magnetic properties of novel single-ion magnets? Single molecule magnets (SMMs) have potential for use as quantum bits (qubits) in quantum information processing devices. SMMs typically have six to twelve high-spin atoms connected to one another via oxygen or nitrogen bridging atoms. Our primary objective is to gain insight into a subset of SMMs called single ion magnets (SIMs) which are usually comprised of a ligand-protected high-spin atom that is trapped in a crystal lattice with fixed SIM-SIM distances. If a gold cluster is doped with a high-spin atom such as Mn, Fe, Co then, due to the greater electronegativity of Au, the high-spin atom will have a positive charge. These species are therefore a novel type of "free standing" SIM that could be arrayed on a surface with optimum SIM-SIM distances. This could result in a qubit with unique functionality.