Dynamic terahertz spectroscopy of gas molecules mixed with unwanted aerosol under atmospheric pressure using fibre-based asynchronous-optical-sampling terahertz time-domain spectroscopy.
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.
Graduate School of Science and Technology, Tokushima University, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.|JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.
Yi-Da
YD
Hsieh
Graduate School of Science and Technology, Tokushima University, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.
Shota
S
Nakamura
Graduate School of Science and Technology, Tokushima University, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.|JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.
Dahi Ghareab
DG
Abdelsalam
Graduate School of Science and Technology, Tokushima University, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.|JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.
Takeo
T
Minamikawa
JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.|Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871, Japan.
Yasuhiro
Y
Mizutani
JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.|Center for Optical Research and Education, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-858, Japan.
Hirotsugu
H
Yamamoto
Graduate School of Science and Technology, Tokushima University, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.|JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.
Tetsuo
T
Iwata
Laboratoire de Physico-Chimie de l'Atmosphère, Université du Littoral Côte d'Opale, 189A Av. Maurice Schumann, Dunkerque 59140, France.
Francis
F
Hindle
Graduate School of Science and Technology, Tokushima University, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.|JST, ERATO, MINOSHIMA Intelligent Optical Synthesizer Project, 2-1, Minami-Josanjima, Tokushima 770-8506, Japan.
Takeshi
T
Yasui