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Zhang Q, Hadizadeh MH, Hu Y, Zhang X, Su Z, Wu Z, Wang X, Xu F, Sun Y, Zhang Q, Wang W. The effects of the gas-liquid interface and gas phase on Cl/ClO radical interaction with water molecules. Phys Chem Chem Phys 2023; 25:23296-23305. [PMID: 37609804 DOI: 10.1039/d3cp02796a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
In the marine boundary layer (MBL), chlorine (Cl) and chlorine monoxide (ClO) are powerful oxidants with high concentrations. The gas-liquid interface is also ubiquitous in the MBL as a favorable site for atmospheric reactions. Understanding the role of water in Cl/ClO radical chemistry is essential for predicting their behavior in the atmosphere and developing effective strategies for mitigating their harmful effects. However, the research studies on the system of Cl/ClO radicals on the surface of water droplets are still insufficient. In previous studies, we have found unique results related to the hydroxyl radical at the interface using ab initio molecular dynamics (AIMD). In this work, we have used AIMD to investigate interactions between Cl/ClO radicals and water molecules at the gas-liquid interface. Radical mobility, radial distribution functions, coordination, and population analyses were conducted to investigate the surface preference, bonding pattern, and track Cl/ClO radicals in the water droplets. In addition, density functional theory (DFT) analysis was conducted to compare the results at the gas-liquid interface with those in the gas phase. We found that Cl/ClO radicals tend to remain near the gas-liquid interface in water droplet systems and outside of water clusters in gas phase systems. The ClO radical can form O*-H and Cl-O bonds with water molecules; however, neither the O*-O hemibond nor the Cl-H bond was detected in all systems. Different dominant structures were obtained for ClO in the interface and gas phase. The ClO radical can be bonded to one water molecule from its oxygen side, (H2O)0-Cl-O*-(H2O)1 at the interface, or to two water molecules from the chlorine and oxygen sides, (H2O)1-Cl-O*-(H2O)1 in the gas phase. Meanwhile, the Cl radical can only form a dominant structure like Cl*-(H2O)1 at the gas-liquid interface by making a Cl*-O hemibond. Providing a thorough explanation of the Cl/ClO radical behavior at the gas-liquid interface, this study will improve our understanding of the MBL's oxidizing capacity and pollution causes.
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Affiliation(s)
- Qi Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Mohammad Hassan Hadizadeh
- Environment Research Institute, Shandong University, Qingdao 266237, China.
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yongxia Hu
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Xiaoyu Zhang
- School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Zupeng Su
- School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Zihan Wu
- School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Xiaotong Wang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Fei Xu
- Environment Research Institute, Shandong University, Qingdao 266237, China.
- Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
| | - Yanhui Sun
- College of Environment and Safety Engineering, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
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Ward MKM, Rowley DM. Kinetics of the BrO + HO 2 reaction over the temperature range T = 246-314 K. Phys Chem Chem Phys 2017; 19:23345-23356. [PMID: 28825741 DOI: 10.1039/c7cp03854b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The kinetics of the reaction between gas phase BrO and HO2 radicals, BrO + HO2 → HOBr + O2 (1), have been studied over the atmospherically relevant temperature range T = 246-314 K and at ambient pressure, p = 760 ± 20 Torr, using laser flash photolysis coupled with ultraviolet absorption spectroscopy. The reaction was initiated by the generation of bromine monoxide radicals following laser photolytic generation of Br atoms from Br2/Cl2 containing mixtures and their reaction with ozone. Subsequently, the addition of methanol vapour to the reaction mixture, in the presence of excess oxygen, afforded the efficient simultaneous post-photolysis formation of HO2 radicals using well-defined chemistry. The decay of BrO radicals, in the presence and absence of HO2, was interrogated to determine the rate coefficients for the BrO + BrO and the BrO + HO2 reactions. A detailed sensitivity analysis was performed to ensure that the BrO + HO2 reaction was unequivocally monitored. The rate coefficient for reaction (1) is described by the Arrhenius expression: where statistical errors are 1σ. The negative temperature dependence of this reaction is in general accord with those reported by previous studies of this reaction. However, the present work reports greater absolute values for k1 than those of several previous studies. An assessment of previous laboratory studies of k1 is presented. This work confirms that reaction (1) plays a significant role in HOBr formation throughout the atmosphere following both anthropogenic, biogenic and volcanic emissions of brominated species. Reaction (1) therefore contributes to an efficient ozone depleting process in the atmosphere, and further confirms the significance of interactions between two different families of reactive atmospheric trace species.
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Affiliation(s)
- Michael K M Ward
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
| | - David M Rowley
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
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