Controlling Vibrationally-mediated Spin Dynamics Using Metal Nanostructure

在化学系大分子、超分子和纳米化学(MSN)计划的支持下，宾夕法尼亚州立大学的Kenneth Knappberger教授将先进的激光技术与磁场相结合，研究金属纳米团簇的结构和原子的运动如何影响其电子的自旋。电子自旋在许多新兴技术中扮演着重要的角色，但由于纳米团簇原子的振动运动导致电子自旋的快速松弛，因此很难对其进行研究。克纳彭伯格教授和他的学生将通过将电子自旋寿命与特定振动模式的相互作用联系起来来应对这一挑战。我们将使用磁场激光光谱和金属纳米团簇合成的迭代过程来了解金属的电子自旋性质。这些基础研究可能会影响基于量子的技术的进步，并导致更高效的催化剂、减少温室气体排放的新材料以及磁性材料和光学开关的发展。该项目将用先进的实验方法教育研究生和本科生，并通过提供研究机会和职业发展活动来影响高中生。胶体单分子膜保护的纳米团簇允许合成结构明确的金属，表现出各种可调的物理性质。该项目正在开发新的配体交换策略，以了解金属纳米团簇中的状态选择性自旋-振动耦合。我们将用变温磁致光致发光光谱来表征暂态电子自旋态，并发展一种傅里叶变换磁致发光技术来测量自旋寿命和自旋振动耦合。在大小从几个原子到几百个原子的金属纳米团簇上进行的实验将显示自旋性质从分子到金属水平的演变。结构分析将使用质谱学、拉曼光谱、紫外可见吸收光谱和圆二色谱以及X射线衍射来完成。金属的结构特殊性预计将导致纳米级金属自旋动力学的准确结构-性质关联，这对于加快催化剂设计和量子信息科学的进展是必要的。这一奖项反映了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。

With support from the Macromolecular, Supramolecular, and Nanochemistry (MSN) program in the Division of Chemistry, Professor Kenneth Knappenberger of Pennsylvania State University is combining advanced laser techniques with magnetic fields to study how the structure of metal nanoclusters and the motion of their atoms affects the spin of their electrons. Electron spin plays an important role in many emerging technologies but is difficult to study because the vibrational motion of the nanocluster atoms results in rapid relaxation of the electron spin. Professor Knappenberger and his students will address this challenge by correlating electron spin lifetimes to interactions with specific vibrational modes. An iterative process of magnetic-field laser spectroscopy and metal nanocluster synthesis will be employed to understand electron spin properties of metals. These fundamental studies could impact the advancement of quantum-based technologies, as well as lead to more efficient catalysts, new materials for reducing greenhouse gases, and the development of magnetic materials and optical switches. The project will educate graduate and undergraduate students in advanced experimental methods, as well as impact high school students by providing research opportunities and career development activities. Colloidal monolayer-protected nanoclusters allow the synthesis of structurally well-defined metals that exhibit a diverse range of tunable physical properties. This project is developing novel ligand-exchange strategies in order to understand state-selective spin-vibrational coupling in metal nanoclusters. Transient electronic spin states will be characterized using variable-temperature magneto-photoluminescence spectroscopy, as well as develop a Fourier transform magneto-photoluminescence technique for measuring spin lifetimes and spin vibrational coupling. Experiments performed on metal nanoclusters ranging in size from just a few atoms up to several hundred will show the evolution of spin properties from the molecular to metallic levels. Structural analysis will be accomplished using mass spectrometry, Raman spectroscopy, UV-Visible absorption and circular dichroism spectroscopies, as well as X-ray diffraction. The structural specificity of the metals is expected to result in accurate structure-property correlations for spin dynamics in nanoscale metals, which is necessary to accelerate progress in catalyst design and quantum information sciences.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.