Here we report a new multiphase reaction mechanism by which Criegee intermediates (CIs), formed by ozone reactions at an alkene surface, convert SO₂ to SO₃ to produce sulfuric acid, a precursor for new particle formation (NPF). During the heterogeneous ozone reaction, in the presence of 220 ppb SO₂, an unsaturated aerosol (squalene) undergoes rapid chemical erosion, which is accompanied by NPF. A kinetic model predicts that the mechanism for chemical erosion and NPF originate from a common elementary step (CI + SO₂) that produces both gas phase SO₃ and small ketones. At low relative humidity (RH = 5%), 20% of the aerosol mass is lost, with 17% of the ozone-surface reactions producing SO₃. At RH = 60%, the aerosol shrinks by 30%, and the yield of SO₃ is <5%. This multiphase formation mechanism of H₂SO₄ by CIs is discussed in the context of indoor air quality and atmospheric chemistry.

中文翻译：

---

臭氧与角鲨烯异相反应过程中形成的Criegee中间体由SO ₂生产硫酸的多相机理

在这里，我们报告了一种新的多相反应机理，通过该机理，烯烃表面上的臭氧反应形成的Criegee中间体（CIs）将SO ₂转化为SO ₃以产生硫酸，硫酸是新颗粒形成（NPF）的前体。在非均相臭氧反应过程中，在220 ppb SO ₂的存在下，不饱和气溶胶（角鲨烯）经历了快速的化学腐蚀，并伴有NPF。动力学模型预测化学腐蚀和NPF的机理源自共同的基本步骤（CI + SO ₂），该步骤同时生成气相SO ₃和小酮。在较低的相对湿度（RH = 5％）下，会损失20％的气溶胶质量，其中17％的臭氧表面反应会产生SO ₃。在RH = 60％时，气溶胶收缩30％，SO ₃的产率<5％。在室内空气质量和大气化学的背景下，讨论了CIs形成H ₂ SO ₄的这种多相形成机理。