中红外波段大气碳同位素激光吸收光谱研究

The Study of Atmospheric Carbon Isotope with Laser Absorption Spectroscopy at the Mid-Infrared Wavelength

大气碳同位素在环境污染源汇示踪和地球化学发展等方面的应用越来越广泛,在其探测技术方面,激光吸收光谱技术具有体积小、可在线、灵敏度高等优点,在气体同位素探测中越来越受到重视。工作中研究了2.7μm波段的分布式反馈激光器(distributed feedback laser,DFB)可调谐半导体激光器的性能,在遵循12 CO_2和13 CO_2同位素分子吸收谱线特征和同位素分子谱线选择原则的基础上,确定了合适的激光器输出波长。结合光程390.3m的新型多次反射池,实现了大气中CO_2分子的δ^(13)C同位素丰度探测。

The applications of atmospheric carbon isotope are becoming more and more important, which are used widely in the transfer tracer of environmental pollution and the geochemical development. So it is significative to develop novel technologies for carbon isotope detection. Currently, the laser absorption spectroscopy compared with other techniques, which has great advantages of small volume, and high sensitivity which realises real-time online testing,. A large number of researchers have paid close attention to gas isotope probing with laser absorption spectroscopy. In this paper, the tunable semiconductor laser DFB of 2.7 μm wavelength is studied as to the performance. At the same time, the absorption lines of 12 CO2 and 13 CO2 isotopic molecules are chosen according to selection principles of the characteristics and the isotope molecules absorption line. On the basis, the appropriate wavelength from the laser output is determined. Afterwards, the δ13 C isotopic abundances of the CO2 molecule are probed in the atmosphere by the laser absorption spectroscopy under the help of the new multi-pass cell with the 690. 3 m optical path length.