Design and Implementation of a Nonlinear Interferometer

在该项目中，由化学部门的化学测量和成像计划资助，塔夫茨大学的Mary Jane Shultz教授将进行一项研究计划，旨在开发和实现一种通用的、普遍适用的非线性干涉仪。该干涉仪基于非线性光谱，和频产生（SFG）；一个潜在的强大的，表面特异性的振动光谱。目前，利用SFG的能量受到SFG非线性特性的阻碍，对光谱解释提出了挑战。最近开发的技术有望对频谱进行线性化，但由于仪器的复杂性和协议的实施导致很大的不确定性而受到阻碍。在类似线性干涉仪的基础上，新设计的精度有望提高三个数量级。提高精度对水溶液界面尤为重要。因此，新仪器将适用于三种系统：乙腈-水，氨-水和冰-空气。这三种系统各有其独特之处：乙腈水是常见的色谱溶剂，氨是唯一重要的基本大气气体，是通过中和酸性气体形成云凝结核的微粒物质的来源，而冰确实塑造了世界。这项研究将构建一种新的仪器，它可以提供前所未有的分辨率来探测微弱但重要的氢键相互作用。了解这些相互作用对于理解水与各种界面（包括细胞膜和其他生物材料、大气污染物和地壳中的矿物质）之间复杂的相互作用至关重要。该项目将在一名博士后助理的协助下进行，并由本科生陪同，包括妇女和代表性不足的少数民族成员。所有人都将接受尖端光谱工具的技术培训。除了这些活动外，舒尔茨小组还积极参与了化学系的COOP（化学组织外展计划），该计划旨在将一线研究带到当地中学，并将有前途的中学生带到大学获得实践经验。

In this project, funded by the Chemical Measurements and Imaging Program of the Chemistry Division, Professor Mary Jane Shultz of Tufts University will conduct a research program that seeks to develop and implement a versatile, generally applicable, nonlinear interferometer. The interferometer is based on nonlinear spectroscopy, sum frequency generation (SFG); a potentially powerful, surface-specific vibrational spectroscopy. Currently tapping the power of SFG is thwarted by the nonlinear nature of SFG, challenging spectral interpretation. Recently developed techniques hold promise for linearizing the spectrum, but are hampered by instrumental complexity and protocol implementation resulting in large uncertainties. Based on similar linear interferometers, the new design is expected to result in a three orders-of-magnitude accuracy improvement. Improved accuracy is particularly critical of aqueous solution interfaces. Thus, the new instrument will be applied to three systems: acetonitrile-water, ammonia-water, and ice-air. These three systems are each of interest in their own right: Acetonitrile-water is a common chromatography solvent, ammonia is the only significant basic atmospheric gas and is the source of particulate matter for cloud condensation nuclei via neutralization of acidic gases, and ice literally shapes the world. The research will construct a new instrument that allows unprecedented resolution for probing weak but important hydrogen-bond interactions. Understanding these interactions is essential for understanding the complex interplay between water and a variety of interfaces including cell membranes and other biological materials, atmospheric pollutants, and minerals in the Earth's crust. The project will be performed with the assistance of a post-doctoral associate accompanied by undergraduate students including women and members of underrepresented minorities. All will receive technical training in cutting-edge spectroscopic tools. In addition to these activities, the Shultz group is an active participant in the departmental COOP (Chemistry Organized Outreach Program) designed to both bring front-line research to local secondary schools and to bring promising secondary students to the University for hands-on experience.