We present a comprehensive computational study of interaction of a SO₂ with water molecules in the gas phase and with the surface of various sized water nanodroplets to investigate the solvation behavior of SO₂ in different atmospheric environments. Born–Oppenheimer molecular dynamics (BOMD) simulation shows that, in the gas phase and at a temperature of 300 K, the dominant interaction between SO₂ and H₂O is _(SO2)S···O_(H2O), consistent with previous density-functional theory (DFT) computation at 0 K. However, at the surface of a water nanodroplet, BOMD simulation shows that the hydrogen-bonding interaction of _(SO2)O···H_(H2O) becomes increasingly important with the increase of droplet size, reflecting a marked effect of the water surface on the SO₂ solvation. This conclusion is in good accordance with spectroscopy evidence obtained previously (J. Am. Chem. Soc. 2005, 127, 16806; J. Am. Chem. Soc. 2006, 128, 3256). The prevailing interaction _(SO2)O···H_(H2O) on a large droplet is mainly due to favorable exposure of H atoms of H₂O at the air–water interface. Indeed, the conversion of the dominant interaction in the gas phase _(SO2)S···O_(H2O) to the dominant interaction on the water nanodroplet _(SO2)O···H_(H2O) may incur effects on the SO₂ chemistry in atmospheric aerosols because the solvation of SO₂ at the water surface can affect the reactive sites and electrophilicity of SO₂. Hence, the solvation of SO₂ on the aerosol surface may have new implications when studying SO₂ chemistry in the aerosol-containing troposphere.

中文翻译：

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SO ₂与水纳米液滴表面的相互作用

我们提出了一种SO ₂与气相中的水分子以及与各种尺寸的水纳米液滴表面相互作用的综合计算研究，以研究SO ₂在不同大气环境中的溶剂化行为。Born-Oppenheimer分子动力学（BOMD）模拟表明，在气相和300 K的温度下，SO ₂和H ₂ O之间的主要相互作用为_{（SO 2）} S··O _{（H 2 O）}，与先前在0 K下进行的密度泛函理论（DFT）计算一致。但是，在水纳米滴的表面，BOMD模拟表明_（SO2） O···H_{（H 2 O）}随着液滴尺寸的增加而变得越来越重要，这反映了水表面对SO ₂溶剂化的显着影响。这一结论是根据先前获得的光谱证据良好（ J.化学会志。 2005， 127，16806; J。化学会志。 2006， 128，3256）。大液滴上的主要相互作用_{（SO 2）} O···H_{（H 2 O）}主要归因于H ₂的H原子的有利暴露在空气-水界面处为O。事实上，在气相中的主导相互作用的转化_{（SO 2）} š...Ô _{（H 2 O）}对水纳米液滴的主要相互作用_{（SO 2）} Ô···ħ _{（H 2 O）}可招致影响SO ₂在大气中的气溶胶，因为SO ₂在水表面的溶剂化会影响SO ₂的反应位和亲电性。因此，当研究含气溶胶对流层中的SO ₂化学时，气溶胶表面上的SO ₂溶剂化可能具有新的含义。