Li Jingsong, Zhang Lizhu, Yu Benli
Key Laboratory of Opto-Electronic Information Acquisition and Manipulation of Ministry of Education, Anhui University, Hefei, China.
School of Science, Tianjin University of Technology and Education, Tianjin, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Dec 10;133:489-94. doi: 10.1016/j.saa.2014.06.052. Epub 2014 Jun 16.
The feasibility of laser spectroscopic isotopic composition measurements of atmospheric N2O was demonstrated, although making them useful will require further improvements. The system relies on a thermoelectrically (TE) cooled continuous-wave (CW) room temperature (RT) quantum cascade laser source emitting wavelength of around 4.6μm, where strong fundamental absorption bands occur for the considered specie and its isotopomers. The analysis technique is based on wavelength modulation spectroscopy with second-harmonic detection and the combination of long-path absorption cell. Primary laboratory tests have been performed to estimate the achievable detection limits and the signal reproducibility levels in view of possible measurements of (15)N/(14)N and (18)O/(16)O isotope ratios. The experiment results showed that the site-selective (15)N/(14)N ratio can be measured with a precision of 3‰ with 90s averaging time using natural-abundance N2O sample of 12.7ppm.
尽管要使其变得有用还需要进一步改进，但已证明了对大气中N2O进行激光光谱同位素组成测量的可行性。该系统依赖于一个热电（TE）冷却的连续波（CW）室温（RT）量子级联激光源，其发射波长约为4.6μm，在所考虑的物种及其同位素异构体中会出现强烈的基频吸收带。分析技术基于具有二次谐波检测的波长调制光谱以及长路径吸收池的组合。鉴于可能对（15）N/（14）N和（18）O/（16）O同位素比率进行测量，已经进行了初步实验室测试以估计可实现的检测限和信号重现性水平。实验结果表明，使用12.7ppm的天然丰度N2O样品，在90秒平均时间下，可以以3‰的精度测量位点选择性（15）N/（14）N比率。
