“…Yet, the reactive uptake coefficient of N 2 O 5 (γ(N 2 O 5 )) and nitryl chloride yield (φ(ClNO 2 )) have important atmospheric implications and are known to depend on particle composition, water content, and morphology. High water content increases γ(N 2 O 5 ) by promoting hydrolysis, and the resulting particulate nitrate can reduce γ(N 2 O 5 ) by up to an order of magnitude in what is called the “nitrate effect” (). , Particulate chloride can enhance γ(N 2 O 5 ) and lead to ClNO 2 formation. ,, Organic carbon coatings have also been shown to reduce γ(N 2 O 5 ), and primary organic aerosol makes up a large mass fraction of BBA and may be present as coatings. ,− The organic carbon component of BBA is a complex mixture of primary and secondary molecules that can undergo heterogeneous and particle-phase reactions, precluding generalizable estimates of organic aerosol composition or properties. , Until recently, γ(N 2 O 5 ) has only been determined with simplified one- or two-component aerosol systems or BBA proxies ,,,, that may not represent authentic BBA and its complex composition and morphology. ,− …”