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Chlorine (Cl) radicals strongly affect atmospheric oxidation and the fate of pollutants. Despite several observations, the potential impacts of nitrogen chemistry associated with NO 2 on Cl chemistry are poorly understood. Here, we provided direct field evidence that the nitrogen chemistry enhancements triggered by the increased NO 2 drove daytime nitrate (NO 3 - ) photolysis and nighttime NO 3 -N 2 O 5 reactions, significantly promoting the increases in the concentrations of ClNO 2 and Cl 2 after the Chinese Spring Festival. The enhancement in the Cl chemistry facilitated the elevations of both O 3 and atmospheric oxidation capacity during the winter daytime. Our findings highlighted the importance of nitrogen chemistry induced by the increased NO 2 in enhanced Cl chemistry.

Two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) shows great potential for developing flexible and wearable spintronic devices by serving as spin sources via the bulk Rashba effect (BRE). However, the practical application of BRE in 2D HOIP faces huge challenges, particularly due to the toxicity of lead, which is crucial for achieving large spin-orbit coupling, and the restrictions in 2D HOIP candidates to meet specific symmetry-breaking requirements. To overcome these obstacles, we designed a strategy to exploit the interfacial Rashba effect (IRE) of lead-free 2D HOIP (C 6 H 5 CH 2 CH 2 NH 3 ) 2 CuCl 4 (PEA-CuCl), manifesting as an efficient spin generator at room temperature. IRE of PEA-CuCl originates from the large orbital hybridization at the interface between PEA-CuCl and adjacent ferromagnetic layers. Spin-torque ferromagnetic resonance measurements further quantify a large Rashba effective field of 14.04 Oe per 10 11 A m -2 , surpassing those of lead-based HOIP and traditional all-inorganic heterojunctions with noble metals. Our lead-free 2D HOIP PEA-CuCl, which harnesses large IRE for spin generation, is efficient, nontoxic, and economic, offering huge promise for future flexible and wearable spintronic devices.

The understanding at a molecular level of ambient secondary organic aerosol (SOA) formation is hampered by poorly constrained formation mechanisms and insufficient analytical methods. Especially in developing countries, SOA related haze is a great concern due to its significant effects on climate and human health. We present simultaneous measurements of gas-phase volatile organic compounds (VOCs), oxygenated organic molecules (OOMs), and particle-phase SOA in Beijing. We show that condensation of the measured OOMs explains 26-39% of the organic aerosol mass growth, with the contribution of OOMs to SOA enhanced during severe haze episodes. Our novel results provide a quantitative molecular connection from anthropogenic emissions to condensable organic oxidation product vapors, their concentration in particle-phase SOA, and ultimately to haze formation.

Sulfur trioxide (SO 3 ) is a crucial compound for atmospheric sulfuric acid (H 2 SO 4 ) formation, acid rain formation, and other atmospheric physicochemical processes. During the daytime, SO 3 is mainly produced from the photo-oxidation of SO 2 by OH radicals. However, the sources of SO 3 during the early morning and night, when OH radicals are scarce, are not fully understood. We report results from two field measurements in urban Beijing during winter and summer 2019, using a nitrate-CI-APi-LTOF (chemical ionization-atmospheric pressure interface-long-time-of-flight) mass spectrometer to detect atmospheric SO 3 and H 2 SO 4 . Our results show the level of SO 3 was higher during the winter than during the summer, with high SO 3 levels observed especially during the early morning (∼05:00 to ∼08:30) and night (∼18:00 to ∼05:00 the next day). On the basis of analysis of SO 2 , NO x , black carbon, traffic flow, and atmospheric ions, we suggest SO 3 could be formed from the catalytic oxidation of SO 2 on the surface of traffic-related black carbon. This previously unidentified SO 3 source results in significant H 2 SO 4 formation in the early morning and thus promotes sub-2.5 nm particle formation. These findings will help in understanding urban SO 3 and formulating policies to mitigate secondary particle formation in Chinese megacities., Competing Interests: The authors declare no competing financial interest.

The use of monoethanolamine (MEA, 2-hydroxyethanamine) for scrubbing of carbon dioxide from combustion flue gases may become the dominant technology for carbon capture in the near future. The widespread implementation of this technology will result in elevated emissions of MEA to the environment that may increase the loading and modify the properties of atmospheric aerosols. We have utilized experimental measurements together with aerosol microphysics calculations to derive thermodynamic properties of several MEA salts, potentially the dominant forms of MEA in atmospheric particles. The stability of the salts was found to depend strongly on the chemical nature of the acid counterpart. The saturation vapor pressures and vaporization enthalpies obtained in this study can be used to evaluate the role of MEA in the aerosol and haze formation, helping to assess impacts of the MEA-based carbon capture technology on air quality and climate change.