Fig. 4: Impact of trace gases on direct H2SO4 formation using ionisation by nitrate.
From: Direct sulfuric acid formation from the gas-phase oxidation of reduced-sulfur compounds
Experiments were conducted either in the free-jet flow system, t = 7.9 s, or in the laminar flow tube (LFT), t = 32 s, at r.h. = 10% (or <0.1%) using tetramethyl ethylene (TME) ozonolysis for OH radical production. Reactant concentrations are given in Supplementary Table 1. Error bars represent the uncertainty of ∼20% in the absolute calibration. Source data are provided as a Source Data file. a Formation of H2SO4 and SO3 as a function of ozone measured in the LFT. Reacted CH3SH was in the range (7.6–17) × 107 and (2.1–18) × 107 molecules cm−3 for DMDS (dimethyl disulfide). b H2SO4 and MSA (methane sulfonic acid) formation from OH + CH3SH depending on RO2 radical concentrations, CH3C(O)CH2O2 and CH3O2, in the LFT. Rising RO2 levels were achieved by stepwise increase of TME and corresponding CH4 additions keeping reacted CH3SH constant at ∼7.6 × 107 molecules cm−3. Highest CH3C(O)CH2O2 and CH3O2 concentrations were 1.0 × 109 and 8.8 × 108 molecules cm−3, respectively, calculated from an extended model (Supplementary Table 4). c H2SO4 formation yields as a function of NO addition. d H2SO4 formation yields as a function of NO2 addition.
