Transient Physicochemical Properties of Nanomaterials

在化学系大分子、超分子和纳米化学项目的支持下，西北大学的Richard Schaller教授将研究半导体和金属纳米颗粒的晶格、表面和表面配体行为，以促进对其物理化学性质的了解。具有纳米级特征的半导体和金属颗粒提供了有益的属性，可用于固态照明、显示器和光伏生物/化学传感器。这项研究项目的研究将在实验上阐明在将纳米材料推向性能极限或明确针对粒子融合的条件下关键特性的平衡和时间演变。该项目将支持未来研究人员在先进实验方法和数据分析领域的培训，并提供关于有前景的材料系统的共同知识方面的进展。实验室的研究方法和结果将被纳入课堂，并在公共场所展示。席勒小组的成员将与社区大学和公立学校进行接触。纳米颗粒和表面配体对强烈激发和高温的反应，无论是脉冲的还是持续的，都会影响光电特性，并影响添加剂制造过程中产生的固体。计划中的研究旨在评估这一影响，但更重要的是，利用各种激发条件下的瞬时X射线衍射和受激拉曼散射到选定区域的电子衍射和核磁共振的方法，为此类系统的演变提供洞察力。拟议的工作试图评估配基重新分配、表面活性、晶格无序、特定组成的解混以及声子分布的演变的过程和相关性。洞察力可以提供将设计的纳米颗粒的稳定性提高到极端条件下的方法，或者相反地，有助于将其整合到颗粒的烧结整体中。将对几种富含稀土和低毒的成分进行研究。总体目标是识别和学习预测纳米粒子结构和化学配体基序如何在技术相关的条件下影响静态和动态物理化学性质。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。

With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Richard Schaller from Northwestern University will investigate crystal lattices, surfaces, and surface ligand behavior of semiconductor and metal nanoparticles to advance understanding of their physicochemical properties. Semiconductor and metal particles with nanometer-scale features offer beneficial attributes that can be exploited for solid-state lighting, displays and photovoltaics to bio/chem sensors. The studies of this research project will experimentally elucidate equilibrium- and time-evolution of key properties under conditions that either push nanomaterials to performance limits or expressly target particle fusion. This project will support training for future researchers in areas of advanced experimental methods and data analysis and offers advances in communal knowledge regarding promising materials systems. Research methods and findings from the lab will be incorporated into the classroom and presented in public venues. Member of the Schiller group will engage in outreach to community colleges and public schools.The response of nanoparticles and surface ligands to intense excitation and elevated temperature, whether pulsed or sustained, impacts optoelectronic characteristics as well as influences the solid produced during additive manufacturing. Planned studies aim to both evaluate this impact but more importantly offer insights as to evolution of such systems using approaches spanning transient x-ray diffraction and stimulated Raman to selected area electron diffraction and nuclear magnetic resonance for a range of excitation conditions. The proposed effort seeks to evaluate processes and relevance of ligand re-partitioning, surface activity, lattice disordering, de-mixing of particular compositions, and evolution of phonon distributions. Insights can offer means to increase stability of as-designed nanoparticles to extreme conditions or conversely facilitate incorporation into a sintering ensemble of particles. Several earth abundant and low toxicity compositions will be investigated. The overall objective is to discern and learn to predict how nanoparticle structure and chemical ligand motif impact static and dynamic physicochemical properties under technologically relevant conditions.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.