Transient Physicochemical Properties of Nanomaterials

在化学系高分子、超分子和纳米化学项目的支持下，西北大学的理查德·沙勒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，以加深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、显示器和光伏发电以及生物/化学传感器。该研究项目的研究将通过实验阐明在将纳米材料推向性能极限或明确目标粒子融合的条件下关键特性的平衡和时间演化。该项目将支持对未来研究人员在先进实验方法和数据分析领域的培训，并提供有关有前途的材料系统的公共知识的进展。实验室的研究方法和研究结果将被纳入课堂并在公共场所展示。 席勒小组的成员将参与到社区大学和公立学校的推广活动。纳米颗粒和表面配体对强烈激发和高温的响应，无论是脉冲的还是持续的，都会影响光电特性以及增材制造过程中产生的固体。计划中的研究旨在评估这种影响，但更重要的是，使用瞬态 X 射线衍射和受激拉曼到选定区域电子衍射和核磁共振的方法，在一系列激发条件下提供有关此类系统演化的见解。拟议的工作旨在评估配体重新分配、表面活性、晶格无序、特定成分的分层以及声子分布演化的过程和相关性。见解可以提供提高所设计的纳米粒子在极端条件下的稳定性的方法，或者相反地促进并入粒子的烧结整体中。将研究几种地球上丰富且低毒性的组合物。总体目标是辨别和学习预测纳米颗粒结构和化学配体基序在技术相关条件下如何影响静态和动态理化性质。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值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.