“…The heterogeneous oxidations are also important pathways to form or bleach BrC, which have been widely studied for the aging of soot and individual organic compounds by OH, O 3 , NO x , SO 2 , and HONO (Baduel et al, 2011;Gallimore et al, 2011;He et al, 2017;Li et al, 2013Li et al, , 2017Pillar-Little and Guzman, 2018, and references therein). Among them, the O 3 aging simulations have been widely conducted, mainly because of O 3 is not only a significant pollutant but also an important oxidant in the atmosphere (Chapleski et al, 2016;Chi et al, 2018;Li et al, 2018). The O 3 oxidation of soot particles generally changes their physicochemical properties (i.e., water solubility, hygroscopicity, size, oxidative potential, and morphology), as well as forms new chromophoric compounds (Decesari et al, 2002;Li et al, 2013;Zhu et al, 2019).…”