CRIF:ID- Development of an Ultrabroad Bandwidth UV-Visible Cavity Enhanced Spectroscopy Spectrometer

这是CRIF:ID项目颁发给弗吉尼亚大学化学系的Kevin K. Lehman、科罗拉多州立大学机械工程系的Azer Yalin和科罗拉多州立大学大气科学系的Sonia M. Kreidenweis的奖项。本项目将设计、制造、测试和表征基于CaF2棱镜的光学腔。由于这种材料的瑞利散射非常低，预计这些棱镜将在整个近紫外和大部分中紫外光谱区域以及可见光区域都很有用。这个光谱区域覆盖了大多数分子的最低电子跃迁。与传统的吸收技术相比，这些棱镜的使用将大大提高灵敏度，对于已知吸收截面的物种，绝对浓度测定可以精确到痕量水平。此外，棱镜腔衰荡光谱系统将与针对分子光谱（Lehmann），溅射测量（Yalin）和大气气溶胶（Kreidenweis）的实验相结合。光谱学是物理科学中应用最广泛的工具之一。紫外、可见光和红外光谱区域的吸收光谱学提供了分子和分子电子结构及其与其他分子相互作用的信息。在荧光较弱的情况下，吸收是检测光学跃迁最直接和实用的方法。虽然吸收光谱学被广泛应用，但它在许多应用中长期存在灵敏度不足的问题。在过去的二十年中，通过引入腔衰荡光谱和开发低损耗（高精细度）光学腔的相关方法，这种灵敏度得到了显着提高，开辟了许多新的应用。目前的工作将导致这些方法的光谱范围和灵敏度的大幅增加，特别是在紫外光谱区域。这些项目将由研究生进行，他们将学习有价值的研究和仪器开发技能。

This is an award from the CRIF:ID program to Kevin K. Lehman in the Chemistry Department at the University of Virginia, Azer Yalin, Mechanical Engineering Department, Colorado State University and Sonia M. Kreidenweis, Atmospheric Science Department, Colorado State University. In the development project optical cavities based upon CaF2 prisms will be designed, fabricated, tested and characterized. Because of the substantially lower Rayleigh scattering of this material, it is anticipated that these prisms will be useful throughout the near and much of the mid-UV spectral regions as well as the visible. This spectral region covers the lowest electronic transitions of most molecules. The use of these prisms will allow a dramatic improvement in sensitivity over conventional absorption techniques and absolute concentration determination down to trace levels for species of known absorption cross section. Further, the prism cavity ring-down spectroscopy systems will be integrated with experiments targeted at Molecular Spectroscopy (Lehmann), measurements of sputtering (Yalin), and atmospheric aerosols (Kreidenweis). Spectroscopy is one of the most widely used tools in physical science. Absorption spectroscopy in the UV, visible, and IR spectral regions give information on the molecular and electronic structures of molecules and their interactions with other molecules. In cases where fluorescence is weak, absorption is the most straightforward and practical way to detect optical transitions. While absorption spectroscopy is widely used, it has long suffered from inadequate sensitivity for many applications. In the past two decades, this sensitivity has been dramatically improved, opening up many new applications, by the introduction of Cavity Ring-down Spectroscopy and related methods that exploit low loss (high finesse) optical cavities. The present work will lead to a substantial increase in the spectral range and sensitivity of these methods, particularly in the UV spectral region. The projects will be carried out by graduate students who will learn valuable research and instrument development skills.