Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy.
Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy.
复制标题
DOI：
10.1038/srep28114
复制
发表时间：
2016-06-15
影响因子：
4.6
通讯作者：
Yasui T
中科院分区：
文献类型：
--
作者：
Hsieh YD;Nakamura S;Abdelsalam DG;Minamikawa T;Mizutani Y;Yamamoto H;Iwata T;Hindle F;Yasui T
太赫兹（THz）光谱是一种很有前途的方法，用于分析极性气体分子与不必要的气溶胶混合，由于其能够获得旋转跃迁的光谱指纹和免疫力气溶胶散射。本文利用一种基于光纤的双光取样THz时域光谱仪，在大气压下对有烟雾存在的乙腈气体进行了动态THz光谱研究。为了匹配大气压下气体分子的THz光谱特征，光谱分辨率被优化为1 GHz，测量速率为1 Hz。当考虑从0.2 THz到1 THz的众多吸收线的所有光谱贡献时，紧密堆积的吸收线的光谱重叠显著地将检测限提高到200 ppm。监测的CH3CN气体浓度的时间变化的烟雾条件下，在大气压力下，在挥发的CH3CN液滴和以下的挥发的CH3CN气体的扩散没有散射或吸收的烟雾的影响。该系统将为常压下气体分析的实际应用，如燃烧过程或火灾事故中目标气体的实时监测提供有力的工具。
Terahertz (THz) spectroscopy is a promising method for analysing polar gas molecules mixed with unwanted aerosols due to its ability to obtain spectral fingerprints of rotational transition and immunity to aerosol scattering. In this article, dynamic THz spectroscopy of acetonitrile (CH3CN) gas was performed in the presence of smoke under the atmospheric pressure using a fibre-based, asynchronous-optical-sampling THz time-domain spectrometer. To match THz spectral signatures of gas molecules at atmospheric pressure, the spectral resolution was optimized to 1 GHz with a measurement rate of 1 Hz. The spectral overlapping of closely packed absorption lines significantly boosted the detection limit to 200 ppm when considering all the spectral contributions of the numerous absorption lines from 0.2 THz to 1 THz. Temporal changes of the CH3CN gas concentration were monitored under the smoky condition at the atmospheric pressure during volatilization of CH3CN droplets and the following diffusion of the volatilized CH3CN gas without the influence of scattering or absorption by the smoke. This system will be a powerful tool for real-time monitoring of target gases in practical applications of gas analysis in the atmospheric pressure, such as combustion processes or fire accident.