| Title: | Absolute determination of chemical kinetic rate constants by optical tracking the reaction on the second timescale using cavity-enhanced absorption spectroscopy |
| Author(s): | Yi H; Meng L; Wu T; Lauraguais A; Coeur C; Tomas A; Fu H; Gao X; Chen W; |
| Address: | "Laboratoire de Physicochimie de l'Atmosphere, Universite du Littoral Cote d'Opale, 59140 Dunkerque, France. chen@univ-littoral.fr. IMT Nord Europe, Institut Mines-Telecom, Univ. Lille, Center for Energy and Environment, 59000 Lille, France. Key Laboratory of Nondestructive Test, Nanchang Hangkong University, Nanchang 330063, China. wutccnu@nchu.edu.cn. Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Institute of Atmospheric Sciences, Fudan University, Shanghai, 200433, China. Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China" |
| ISSN/ISBN: | 1463-9084 (Electronic) 1463-9076 (Linking) |
| Abstract: | "We report a new spectroscopic platform coupled to an atmospheric simulation chamber for the direct determination of chemical rate constants with high accuracy at a second time-scale resolution. These developed analytical instruments consist of an incoherent broadband cavity enhanced absorption spectrometer using a red light emitting diode (LED) emitting at approximately 662 nm (LED-IBBCEAS) associated with a multipass cell direct absorption spectrometer (MPC-DAS) coupled to an external cavity quantum cascade laser (EC-QCL) operating in the mid-infrared region at approximately 8 mum (EC-QCL-MPC-DAS). Spectrometers were employed to investigate the NO(3)-initiated oxidation of four selected volatile organic compounds (VOCs) for the determination of the corresponding rate constants with a dynamic range of 5 orders of magnitude (from 10(-11) to 10(-16) cm(3) molecule(-1) s(-1)). Rate constants of (6.5 +/- 0.5) x 10(-15), (7.0 +/- 0.4) x 10(-13), and (5.8 +/- 0.5) x 10(-16) cm(3) molecule(-1) s(-1) for propanal, isoprene and formaldehyde, respectively, were directly determined by fitting the measured concentration-time profiles of NO(3) and VOCs (measured using a proton transfer reaction time-of-flight mass spectrometer, PTR-ToF-MS) to chemical models based on the FACSIMILE simulation software (version 4.2.50) at 760 torr and 293 +/- 2 K. The obtained rate constants are in good agreement with the most recent recommendations of the IUPAC (International Union of Pure and Applied Chemistry). In addition, a rate constant of (2.60 +/- 0.30) x 10(-11) cm(3) molecule(-1) s(-1) for the oxidation of 2-methoxyphenol by NO(3) radicals was first determined using the absolute kinetic method. Compared to the mostly used indirect relative rate method, the rate constant uncertainty is reduced from approximately 20% to approximately 12%. The results demonstrated the high potential of using modern spectroscopic techniques to directly determine the chemical reaction rate constants" |
| Notes: | "PubMed-not-MEDLINEYi, Hongming Meng, Lingshuo Wu, Tao Lauraguais, Amelie Coeur, Cecile Tomas, Alexandre Fu, Hongbo Gao, Xiaoming Chen, Weidong eng England 2022/03/11 Phys Chem Chem Phys. 2022 Mar 23; 24(12):7396-7404. doi: 10.1039/d2cp00206j" |
