Very High Sensitivity Spectrometer for Atmospheric Measurements

准确测量大气中痕量气体的浓度或通量对大气研究的许多领域至关重要。基于可调谐半导体激光吸收光谱的仪器对多种大气物种的检测具有广泛的通用性。然而，到目前为止，这种系统通常体积庞大，操作起来笨拙，而且对于测量低浓度大气中的一些重要物种没有足够的灵敏度。该项目的目标是开发一种使用单模液氮冷却铅盐二极管激光器的快速响应、高灵敏度的传感器。在该计划的第一阶段，开发了显著减少多程吸收池中的光学条纹问题的技术。这些条纹通常是实现高灵敏度的限制因素。第二阶段研究的主要目标是进一步提高红外半导体激光吸收的灵敏度，以及简化使用红外光纤的仪器设计的研究方法。将组装一台原型光谱仪，用于环境过氧化氢浓度的本地现场测量，以演示对痕量大气物种的超灵敏、实时检测。第二阶段研究的结果将为第三阶段大气研究仪器的商业开发提供所需的设计信息。

The accurate measurement of concentrations or fluxes of trace gases in the atmosphere is crucial to many areas of atmospheric research. Instrumentation based on tunable diode laser absorption spectroscopy has wide generality for detection of many atmospheric species. To date, however, such systems have usually been bulky and awkward to operate and do not have adequate sensitivity for the measurement of a number of important species in the atmosphere at low concentrations. The goal of this program is to develop a rapid response, high sensitivity sensor using single-mode liquid nitrogen- cooled lead-salt diode lasers. In Phase I of this program, techniques that substantially reduce the problem of optical fringes in multiple pass absorption cells were developed. These fringes are often the limiting factor for achieving high sensitivity. The major objectives of the Phase II research are to improve further the sensitivity for infrared diode laser absorption and the study methods for simplifying instrument design using infrared fiber optics. A prototype spectrometer will be assembled for local field measurements of ambient hydrogen peroxide concentrations in order to demonstrate ultrasensitve, real-time detection of trace atmospheric species. Results of the Phase II study will provide the required design information for Phase III commercial development of instrumentation for atmospheric research.