Particulate sulfuric acid and methanesulfonic acid (MSA) are known to form through oxidation of reduced sulfur compounds, however, the mechanisms by which these compounds form are not well understood. Additionally, the aerosol yields and ratio of MSA to sulfuric acid particulate formation are not well documented, making it difficult to estimate the health and climate impacts of reduced sulfur compounds. To investigate these unknowns, dimethylsulfide (DMS) and dimethyldisulfide (DMDS) were oxidized, using a variety of oxidants, in a 37.5 cubic meter Teflon environmental chamber with relative humidity ranging from 2% to 55%. The mass fraction of particulate MSA was estimated based on unique aerosol fragments, at m/z 79 and 96, measured by a High Resolution Time-of-Flight Mass Spectrometer. MSA to sulfuric acid particulate ratios varied depending on initial conditions. This study revealed that substantial water vapor is necessary to form MSA. The mass fraction of MSA increases in the presence of ${\text{NO}}_{\text{x}}.$ Nitrate radical oxidation of DMS and DMDS resulted in nearly 100% of the aerosol estimated to be MSA, suggesting nighttime chemistry may play an important role in ambient MSA formation. This study builds upon results from similar experiments, presented in Van Rooy et al. (2021), which were conducted under extreme dry conditions.

已知颗粒硫酸和甲磺酸 (MSA) 是通过还原硫化合物的氧化形成的，但是，这些化合物形成的机制尚不清楚。此外，MSA 与硫酸颗粒形成的气溶胶产量和比率没有得到很好的记录，因此难以估计减少的硫化合物对健康和气候的影响。为了研究这些未知物，在相对湿度为 2% 至 55% 的 37.5 立方米特氟龙环境室中，使用各种氧化剂氧化二甲基硫醚 (DMS) 和二甲基二硫醚 (DMDS)。颗粒 MSA 的质量分数是根据 m/z 79 和 96 处的独特气溶胶碎片估算的，由高分辨率飞行时间质谱仪测量。MSA 与硫酸的颗粒比随初始条件而变化。这项研究表明，大量的水蒸气是形成 MSA 所必需的。MSA 的质量分数在存在下增加${\text{不}}_{\text{X}}.$DMS 和 DMDS 的硝酸根自由基氧化产生了几乎 100% 的估计为 MSA 的气溶胶，这表明夜间化学可能在环境 MSA 形成中起重要作用。这项研究建立在 Van Rooy 等人提出的类似实验的结果之上。(2021)，这是在极端干燥条件下进行的。