Solvation, Spectroscopy and Dynamics in Supercritical and Expanded Solvents

在这个由化学部实验物理化学项目资助的项目中，Maroncelli将研究超临界流体（SCF）和膨胀液体混合物中的溶剂化、光谱学和动力学。计算和光谱技术将被用于在分子水平上了解其临界点附近的流体环境。静态和时间分辨电子能谱和分子动力学模拟将应用于研究溶剂化及其对原型偶极、四极和非偶极溶剂中激发态电荷转移反应的影响。超临界流体中溶质的时间分辨斯托克斯位移实验将探索局部溶质-溶剂动力学。气体膨胀液体将被研究作为可能有选择性沉淀能力的潜在反溶剂。该项目的研究结果不仅将影响超临界流体的研究，而且将影响更一般的领域，如常规液体动力学、偶极和离子溶剂化、介电摩擦、光学线形状、光谱位移和相互作用势的建模。液体中的分子相互作用以及溶剂和溶质分子之间的相互作用一直是许多研究的对象。超临界流体是处于低密度状态的物质，没有液态和气态的区别。目前，由于在材料加工中可能有有趣的和技术上重要的应用，超临界流体正受到相当大的关注。然而，我们对这些复杂系统的理解还远远不够。在这个项目中，实验和模拟的平衡结合将为溶质和溶剂的模型提供关键的测试，并帮助培养学生在技术和基础相关的不断发展的领域。

In this project funded by the Experimental Physical Chemistry Program of the Chemistry Division, Maroncelli will study solvation, spectroscopy, and dynamics in supercritical fluids (SCF) and expanded-liquid mixtures. Computational and spectroscopic techniques will be used to obtain a molecular-level understanding of fluid environments near their critical points. Static and time-resolved electronic spectroscopy and molecular dynamics simulations will be applied to study solvation and its influence on excited-state charge-transfer reactions in prototypical dipolar, quadrupolar and nondipolar solvents. Time-resolved Stokes-shift experiments on solutes in supercritical fluids will probe local solute-solvent dynamics. Gas-expanded liquids will be studied as potential anti-solvents that may be capable of selective precipitation. Results of this project will impact not only research on supercritical fluids, but also more general areas such as the dynamics of regular liquids, dipolar and ion solvation, dielectric friction, optical line shapes, spectral shifts, and modelling of interaction potentials.The molecular interactions within a liquid and those between solvent and solute molecules have been the object of numerous studies. Supercritical fluids are materials in a low density state that lacks the distinction between liquid and gaseous states. Currently SCFs are receiving considerable attention due to the possibility of interesting and technologically important applications in materials processing. However, our understanding of these complex systems is far from complete. The well balanced combination of experiments and simulation in this project will provide critical tests for models of solutes and solvents and helps train students in a growing field with both technological and fundamental relevance.