Importance of secondary organic aerosol formation of <i>α</i>-pinene, limonene, and <i>m</i>-cresol comparing day- and nighttime radical chemistry

Abstract. The oxidation of biogenic and anthropogenic compounds leads to the formation secondary organic aerosol mass (SOA). present study aims investigate α-pinene, limonene, m-cresol with regards their SOA potential dependent on relative humidity (RH) under night- (NO3 radicals) daytime conditions (OH resulting chemical composition. It was found that limonene NO3 dry significantly exceeds OH-radical reaction, yields 15–30 % 10–21 %, respectively. Additionally, nocturnal yield be very sensitive towards RH, yielding more conditions. In contrast, α-pinene slightly independent from RH. On average, yielded about 6–7 radicals 3–4 reaction. Surprisingly, unexpectedly high were for OH (3–9 %), highest elevated RH (9 which is most likely attributable a higher fraction 3-methyl-6-nitro-catechol (MNC). While mainly composed water-soluble compounds, 50–68 22–39 are water-insoluble. SOA-bound peroxides originated varied between 2 80 as function Furthermore, revealed pinonic acid important particle-phase constituent day- nighttime 1–4 %. Other detected norpinonic (0.05–1.1 fraction), terpenylic (0.1–1.1 pinic (0.1–1.8 3-methyl-1,2,3-tricarboxylic (0.05–0.5 fraction). All marker showed fractions when formed during almost no effect night.