Sum frequency studies of liquid interfaces

Kenneth Eisenthal获得了化学部化学结构，动力学和机制计划的奖项，以开发和应用二次谐波产生（SHG）和和频率产生（SFG）作为选择性探测基本科学兴趣界面的方法。 PI和他的研究小组专注于贵金属纳米颗粒与悬浮液体的界面。 他们提出的中心问题是“贵金属纳米颗粒如何影响位于纳米颗粒/液体界面的激发电子态分子耗散能量的物理机制”？ 利用飞秒SFG和SHG，他们探测激发电子态界面分子的超快衰减。 由于贵金属纳米颗粒特殊的光学和电子学性质，新的能量弛豫通道变得重要。SFG和SHG仅对界面分子敏感，并且不敏感，因此不会被本体液体中大得多的分子群体压倒。 使用SFG和SHG，他们测量界面分子在基态、激发单重态和三重态的振动和电子光谱。由于芳香族羰基化合物具有特殊的光化学和物理性质，因此本研究对探索直接影响太阳能电池、发光二极管、纳米电子学和纳米光学效率的竞争性能量衰减过程的方法和工具具有重要的技术意义。这些方法与各种各样的领域有关，包括卫生保健、电子、纳米技术和替代能源等新兴技术。

Kenneth Eisenthal is supported by an award from the Chemical Structure, Dynamics and Mechanisms program in the Chemistry division to develop and apply second harmonic generation (SHG) and sum frequency generation (SFG) as methods to selectively probe interfaces of fundamental scientific interest. The PI and his research group focus on the interfaces of noble metal nanoparticles with the liquids in which they are suspended. The central question they ask is "how do noble metal nanoparticles affect the photophysical mechanisms by which molecules in excited electronic states, located at the nanoparticle/liquid interface, dissipate their energy"? Using femtosecond SFG and SHG they probe the ultrafast decay of interfacial molecules in excited electronic states. Because of the special optical and electronic properties of noble metal nanoparticles new channels for energy relaxation become important. SFG and SHG are sensitive to interfacial molecules only and are not sensitive and thus not overwhelmed by the much larger population of molecules in the bulk liquid. Using SFG and SHG, they measure the vibrational and electronic spectra of interfacial molecules in their ground, excited singlet, and triplet states. The molecules of interest are the aromatic carbonyls because of their special photophysical and photochemical properties.This research is of technological importance in developing methods and tools to probe the competing energy decay processes that directly impact the efficiency of solar cells, light emitting diodes, nano-electronics and nano-optics. These methods are relevant to a wide variety of fields, including emerging technologies in health care, electronics, nanotechnology and alternative energy.