Presidential Young Investigator Award

米勒教授研究的主要主题是了解凝聚介质中电子传输和能量传输所涉及的主要过程。目前，他的团队正在研究单晶液界面上界面电子转移的动力学，以及随后电荷转移对溶液结构的影响。这一过程的时间分辨动力学与电子转移步骤的机制密切相关，对电子转移步骤的详细了解对其基本性质及其在表面化学中的应用都是重要的。界面电子转移发生在皮秒时间尺度上(10-12秒)，空间维度只有几埃。为了研究这一现象，他们正在利用皮秒激光光谱学和半导体技术的最新发展。随着高效半导体液结光伏技术的出现，以高量子产率光学触发界面电子转移过程成为可能。超灵敏技术，如皮秒瞬变光栅或电光采样，正被用来选择性地原位研究电子转移动力学。未来的研究将包括使用最近开发的量子井半导体液结器件，该器件提供单能电子，专门研究伴随着液体界面电子转移的外球(溶剂)或内球(分子内)复极化现象。其最终目的是提供界面电子转移动力学的详细研究，这将作为电子转移微观模型的有价值的试验场。同时，米勒教授感兴趣的是，在溶液相的放热反应中，多余的能量是如何重新分配的。这种兴趣与他对界面电子转移的光学研究密切相关，该研究涉及在极快的时间尺度上耗散1 eV过剩能量。对于不同的分子体系，到达溶剂晶格的振动能弛豫路径是非常不同的。这些差异现在才开始被理解。解决这一问题的新方法包括使用皮秒瞬时热栅的形成和振动高激发分子的反斯托克斯拉曼研究。

The main theme of Professor Miller's research is to understand the primary processes involved in electron transport and energy transport in condensed media. Currently, his group is investigating the dynamics of interfacial electron transfer at a single crystal liquid interface and the subsequent effect of the charge transfer on the solution structure. The time resolved dynamics of this process are intimately related to the mechanism for the electron transfer step, a detailed understanding of which is important both for its fundamental nature and its application in surface chemistry. Interfacial electron transfer occurs on a picosecond timescale (10-12 sec) over spatial dimensions of only a few angstroms. In order to study this phenomenon, they are taking advantage of recent developments in picosecond laser spectroscopy and semiconductor technology. With the advent of efficient semiconductor liquid junction photovoltaics, it is now possible to optically trigger the interfacial electron transfer process with high quantum yield. Ultrasensitive techniques such as picosecond transient grating or electro-optic sampling are being used to selectively study, in-situ, the electron transfer dynamics. Studies in the future will involve the use of recently-developed quantum well semiconductor liquid junction devices that provide monoenergetic electrons to study exclusively the phenomena of outer sphere (solvent) or inner sphere (intramolecular) repolarization that accompanies electron transfer at a liquid interface. The ultimate goal is to provide a detailed study of interfacial electron transfer dynamics which will serve as a valuable testing ground for microscopic models of electron transfer. Concurrently, Professor Miller is interested in how excess energy is repartitioned during an exothermic reaction in the solution phase. This interest is intimately linked to his optical studies of interfacial electron transfer which involves dissipation of 1 eV excess energy on an extremely fast timescale. Vibrational energy relaxation pathways to the solvent lattice are very different for different molecular systems. These differences are only now beginning to be understood. New approaches to this problem involve the use of picosecond transient thermal grating formation and Antistokes Raman studies of vibrationally highly excited molecules.