Collaborative Research: Development of a Diode Laser Cavity-Ringdown Spectrometer for Shipboard Measurements of the Stable Isotopes on Oceanic Methane

研究所建议开发一种腔衰荡光谱仪，能够在研究船上测量甲烷浓度和稳定同位素（<$2 H-CH 4和<$13 C-CH 4），其精度与标准实验室技术相当。一个便携式的原型已经开发，已达到0.01%的标准误差的测量再现性。这意味着灵敏度为4 ppb，同位素精度与使用Isotope实现的精度相似。这个吗？最基本的将改进原型，使其更适合船基研究。主要的设计修改包括：1）通过锁定和绝缘增加热和振动隔离，2）通过结合声光调制器、半导体光放大器和多个激光器增加采样率，3）使用FM光谱锁定吸收峰的能力，以及4）通过购买可以光纤耦合在一起的组件来最小化对未对准的敏感性。将开发一种前端采样器，用于从一系列充满海水、沉积物或游离气体的血清瓶中自动提取CH 4，并将其注入分析腔。拥有一种现场便携式仪器，可以对<$2 H-CH 4和<$13 C-CH 4进行高精度测量，将有助于海洋学研究的许多领域（例如极端环境中的生命、气候变化、石油研究、碳循环DL-CRDS将允许进行几乎无限数量的分析，大大提高对正在调查的任何CH 4系统的了解，并且由于这些测量是基于船舶的，因此也可以用于指导同一考察期间的后续采样。 该提案旨在开发一种革命性的新的甲烷稳定同位素测量系统。 如果该系统能够成功地开发用于远洋船舶，那么将产生大量甲烷数据，并有望相应地增加对全球甲烷收支汇和源的了解。实现一个用户友好的和紧凑的设备的基础上，光谱（几个二极管激光源耦合到一个高精细腔的高灵敏度和快速CRDS测量方案）的甲烷同位素比测量将在环境科学的研究实验室的高度兴趣。该项目将培养博士后，研究生和本科生，并将加强跨学科的合作伙伴关系。研究结果将传播给更广泛的科学受众，并使人们更好地了解地理问题。

The PIs propose to develop a Cavity-Ringdown Spectrometer (CRDS) capable of measuring methane concentration and stable isotopes (ä2H-CH4 and ä13C-CH4) on a research vessel with a precision comparable to standard laboratory techniques. A portable prototype has been developed that has achieved a measurement reproducibility of 0.01 % standard error. This translates to a sensitivity of 4 ppb and an isotopic precision similar to what is achieved using Isotope. This ?bare-bones? prototype will be advanced to make it more robust for ship-based research. The principal design modifications include: 1) increased thermal and vibrational isolation with caging and insulation, 2) increased sampling rates by incorporating acousto-optic modulators, semiconductor optical amplifiers, and multiple lasers, 3) the ability to lock onto an absorption peak using FM spectroscopy, and 4) minimized susceptibility to misalignment by purchasing components that can be fiber optically coupled together. A front-end sampler will be developed to automatically extract CH4 from an array of serum vials filled with seawater, sediment, or free gas and inject it into the analysis cavity.Having a field-portable instrument that can make high-precision measurements of ä2H-CH4 and ä13C-CH4 will be useful in many areas of oceanographic research (e.g. life in extreme environments, climate change, petroleum research, carbon cycling A DL-CRDS will allow a nearly limitless number of analyses to be conducted, greatly enhancing the understanding of any CH4 system under investigation and since these measurements are ship-based, can also be used to guide subsequent sampling during the same expedition.Broader Impacts: This proposal is aimed at developing a revolutionary new measurement system for the stable isotopes of methane. If the system can be successfully developed to work on ocean-going vessels, then there will be a potential explosion in the amount of methane data that will be produced and, hopefully, a corresponding increase in the understanding of methane budgets sinks and sources worldwide. The realization of a user-friendly and compact device based on optical spectroscopy (several diode laser sources coupled to a high finesse cavity for a high sensitivity and fast CRDS measurement scheme) for methane isotopic ratios measurement will present a high interest for research laboratories in environmental sciences. This Project will train post-docs, graduated and undergraduate students and it will enhance cross disciplinary partnerships. The results will be disseminated to a wider scientific audience and a better understanding of geographical problems will be achieved.