Synergetic effects of NH<sub>3</sub> and NO<sub><i>x</i></sub> on the production and optical absorption of secondary organic aerosol formation from toluene photooxidation

Abstract. NH3 is the most important alkaline gas in atmosphere and one of key species affecting behaviors atmospheric aerosols. However, impact on secondary organic aerosol (SOA) formation remains poorly understood, especially dynamic evolution chemical compositions SOA process. In this study, a series chamber experiments were performed to probe individual common effects NOx toluene through OH photooxidation. The characterized using Aerodyne high-resolution time-of-flight mass spectrometer (AMS). yield increased from 28.1 % absence 34.7 presence but decreased 19.5 NOx. highest 42.7 lowest carbon oxidation state (OSC) occurred both NOx, indicating that higher-volatility products formed could partition into particle phase when was added. This resulted synergetic effect co-existed. heterogeneous reaction main pathway by which participated photooxidation also observed optical absorption. A peak at 280 nm, characteristic organonitrogen imidazole compounds, NH3, its intensity added chamber. work improves our understanding how synergistic interactions between influence offers new insights mitigating haze pollution.