Cavity-Vibration Mixed States: Chemistry in Etalons

分子的振动频率通常与红外光（夜视技术中重要的波长范围）相对应。标准子是由两个平行的反射金属板组成的光学器件，其间距对应于红外波长（大约1微米到1毫米）。如果分子以合适的间距被放置在一个标准子中，它们的振动特性就会发生变化。分子+腔系统被称为“混合状态”，这是光和物质的有趣组合。由于分子振动在分子如何进行化学反应中起着非常重要的作用，因此有可能通过简单地改变腔间距，我们可以改变分子的振动特性以及它们的反应性。在化学结构、动力学和机理a项目的支持下，俄亥俄州立大学的James Coe教授和他的研究生们试图证明制造红外标准子腔模式和凝聚相振动的混合状态来改变反应速率的可行性。“标准子中的化学”将代表一个全新的化学领域，并可能为更有效地生产化学品提供重要的机会。参与该项目的学生在高级光谱学和理论化学计算方面都获得了经验。科教授还计划与加州州立大学多明格斯山分校（Dominguez Hills）的教授合作，该校的学生来自不同种族和经济背景。该项目从可对齐和可调节的标准龙的构造开始，以产生可变宽度的标准龙条纹。标准子充满了具有感兴趣的振动的凝聚态物质。标准子条纹被调整成与振动共振的角度，红外透射光谱被记录下来，从而可以测量拉比分裂——空腔和振动混合状态之间的能量差。为了使测量的拉比分裂与基本量子力学性质（如偶极导数）相关，我们的模型表明，标准子条纹宽度和振动跃迁宽度应该是相同的。由于振动特征显示出很宽的宽度范围，因此需要能够仔细设计与分子振动相匹配的标准子。本项目的重点是：1)标准子条纹宽度对测量的拉比分裂的影响，2)水中CO2的共轭双键系统，3)拓宽气相系统，所有这些都是为了建立这些测量与基本量子力学性质的关系。最后，根据前面的结果，在波长尺度的标准子腔内研究了选定的反应，然后通过红外透射光谱来评估反应速率是否会受到腔和振动的混合状态的影响。虽然这个项目寻求对标准子-分子混合状态的基本见解，但它在广泛的技术应用中具有潜在的意义，包括化学和纳米颗粒传感器，甚至在多相催化中（例如，标准子镜可以作为催化剂或催化剂载体）。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Molecules typically vibrate at frequencies that correspond to infrared light (the wavelength range important in night vision technologies). Etalons are optical devices that consist of two parallel reflective metal plates whose spacing corresponds to infrared wavelengths (roughly 1 micrometer to 1 millimeter). If molecules are placed inside an etalon with just the right spacing, their vibrational properties can change. The molecule+cavity system is called a "mixed state", an interesting combination of light and matter. Since molecular vibrations have very important roles in how molecules undergo chemical reactions, there is the possibility that by simply changing cavity spacings, we can change vibrational properties of the molecules as well as their reactivity. In this project supported by the Chemical Structure, Dynamics and Mechanisms-A Program of the Division of Chemistry, Professor James Coe and his graduate students at The Ohio State University seek to demonstrate the feasibility of making mixed states of infrared etalon cavity modes and condensed phase vibrations to change reaction rates. "Chemistry in Etalons" would represent an entirely new field of chemistry, and may offer significant opportunities for producing chemicals more efficiently. The students involved in this project are gaining experience in both advanced optical spectroscopy and theoretical chemistry calculations. Professor Coe also plans to collaborate with professors at Cal State Dominguez Hills, which has an ethnically and economically diverse student body. The project begins with the construction of alignable and adjustable etalons in order to produce etalon fringes of variable width. The etalon is filled with a condensed phase material which has vibrations of interest. Etalon fringes are angle-tuned into resonance with the vibrations and an infrared transmission spectrum is recorded which enables the measurement of Rabi splittings--the energy difference between the mixed states of cavity and vibration. In order for the measured Rabi splittings to be related to fundamental quantum mechanical properties such as dipole derivatives, our models show that the etalon fringe width and vibrational transition width should be the same. Since vibrational features show a wide range of widths, there is a need to be able to carefully design etalons that match molecular vibrations. This project is focusing on: 1) the effect of etalon fringe width on measured Rabi splittings, 2) the conjugated double bond system of CO2 in water, and 3) broadened gas phase systems, all in order to establish the relation of these measurements to fundamental quantum mechanical properties. Finally, selected reactions are being studied within the wavelength-scale etalon cavity as informed by the previous results and as followed by infrared transmission spectra that allow assessment of whether the rates of reactions can be affected by mixed states of cavities and vibrations. While this project seeks fundamental insights into etalon-molecule mixed states, there is a potential for implications in a wide range of technological applications, including chemical and nanoparticle sensors, and even in heterogeneous catalysis (e.g., the etalon mirrors could serve as catalysts or catalyst supports).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.