Development of a miniturized intra-cavity spectrometer to determine 14CH4 in the field

该项目的目的是研究一种新的小型化装置，用于同位素选择性检测甲烷，检测限为10 ppq或更高。它将提供证据，证明所提议的设备能够确定该领域温室气体的来源和年龄。因此，MUIR使基础气候研究的一个新类别的研究成为可能，因为同位素解析的温室气体浓度研究第一次区分了12CH4、13CH4、12CH3D和14CH4。由于该设备比目前的解决方案更坚固、更小、更简单，因此特别适合于对温室气体源和汇的大面积监测。结合所谓的兜帽测量，可以在大范围内收集有关温室气体起源和年龄的新知识。由于MUIR装置的原位能力，同位素解析分析将能够监测大的空间和时间尺度，这是目前可用技术无法实现的。为了达到低检测限，采用了一种腔内吸收光谱（ICAS）装置，在该装置中，两种模式可以在有源谐振器中振荡。与目前使用的设置相比，这使得可以显着简化信号评估，并使其适用于现场。在MUIR中，He-Ne混合物被用作活性介质。在3.39 μm处的ne -激光跃迁与甲烷的ν3（P7）跃迁几乎重合。在塞曼效应的帮助下，激光跃迁适应于各自甲烷同位素的共振频率。气体样品在分析前经过过滤和预浓缩。通过减少碰撞展宽，微流体系统降低了测量室中的压力，使得同位素分解测量成为可能。

The aim of the project is to research a new, miniaturized device for isotope-selective detection of methane with a detection limit of 10 ppq or better. It will provide evidence that the proposed device is able to determine the origin and age of greenhouse gases in the field. MUIR thus enables a new class of studies in basic climate research, since for the first time the isotope-resolved study of greenhouse gas concentrations distinguishing between 12CH4, 13CH4, 12CH3D, and 14CH4 is made possible. Since the device can be built more robust, significantly smaller and simpler than current solutions, it is particularly suitable for large-area monitoring of greenhouse gas sources and sinks. In combination with so-called hood measurements, new knowledge about the origin and age of greenhouse gases can be gathered over large areas. Due to the insitu capability of the MUIR device, the isotope-resolved analysis will be enable monitoring large spatial and temporal scales, which is notpossible with currently available technologies. In order to achieve the low detection limits, an intracavity absorption spectroscopy (ICAS) setup is used, in which exactly two modes can oscillate in the active resonator. This makes it possible to significantly simplify the signal evaluation as compared to currently used setups and to make it suitable for the field. A He-Ne mixture is used as the active medium in MUIR. The Ne-laser transition at 3.39 μm almost overlaps with the ν3(P7) transition of methane. With the help of the Zeeman effect, the laser transition is adapted to the resonance frequencies of therespective methane isotopes. Gas samples are filtered and pre-concentrated prior to analysis. The isotope-resolved measurement is made possible by reducing collision broadening, for which a microfluidic system reduces the pressure in the measuring chamber.