Find in Library

<p>The reactions between <span class="inline-formula">SO₃</span> and atmospheric acids are indispensable in improving the formation of aerosol particles. However, relative to those of <span class="inline-formula">SO₃</span> with organic acids, the reaction of <span class="inline-formula">SO₃</span> with inorganic acids has not received much attention. Here, we explore the atmospheric reaction between <span class="inline-formula">SO₃</span> and <span class="inline-formula">H₂SO₄</span>, a typical inorganic acid, in the gas phase and at the air–water interface using quantum chemical (QC) calculations and Born–Oppenheimer molecular dynamics simulations. We also report the effect of <span class="inline-formula">H₂S₂O₇</span>, the product of the reaction between <span class="inline-formula">SO₃</span> and <span class="inline-formula">H₂SO₄</span>, on new particle formation (NPF) in various environments using the Atmospheric Cluster Dynamics Code (ACDC) kinetic model and QC calculations. The present findings show that the gas-phase reactions of <span class="inline-formula">SO₃</span> <span class="inline-formula">+</span> <span class="inline-formula">H₂SO₄</span> without and with water molecules are both low-energy-barrier processes. With the involvement of interfacial water molecules, <span class="inline-formula">H₂O</span> induced the formation of the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">S</mi><mn mathvariant="normal">2</mn></msub><msubsup><mi mathvariant="normal">O</mi><mn mathvariant="normal">7</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup><mi mathvariant="normal">⋯</mi><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">3</mn></msub><msup><mi mathvariant="normal">O</mi><mo>+</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="69pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="8bab1a857614ba33fa860bd7ca33c980"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-4029-2024-ie00001.svg" width="69pt" height="17pt" src="acp-24-4029-2024-ie00001.png"/></svg:svg></span></span> ion pair, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M18" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">HSO</mi><mn mathvariant="normal">4</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="33pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="7e06cfafb18f0bdd228533c75b03dfb9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-4029-2024-ie00002.svg" width="33pt" height="16pt" src="acp-24-4029-2024-ie00002.png"/></svg:svg></span></span> mediated the formation of the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msubsup><mi mathvariant="normal">HSO</mi><mn mathvariant="normal">4</mn><mo>-</mo></msubsup><mi mathvariant="normal">⋯</mi><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">3</mn></msub><msup><mi mathvariant="normal">O</mi><mo>+</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="68pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="02b208f57761dd55cffd98206e4bee07"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-4029-2024-ie00003.svg" width="68pt" height="16pt" src="acp-24-4029-2024-ie00003.png"/></svg:svg></span></span> ion pair, and the deprotonation of <span class="inline-formula">H₂S₂O₇</span> was observed and proceeded on the picosecond timescale. The present findings suggest the potential contribution of the <span class="inline-formula">SO₃</span>–<span class="inline-formula">H₂SO₄</span> reaction to NPF and aerosol particle growth, showing that (i) although <span class="inline-formula">H₂S₂O₇</span> is easily hydrolyzed with water to form <span class="inline-formula">H₂SO₄</span>, it can directly participate in <span class="inline-formula">H₂SO₄</span>–<span class="inline-formula">NH₃</span>-based cluster formation and can present a more obvious enhancement effect on <span class="inline-formula">SA</span>–<span class="inline-formula">A</span>-based cluster formation, and (ii) the formed interfacial <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M29" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">S</mi><mn mathvariant="normal">2</mn></msub><msubsup><mi mathvariant="normal">O</mi><mn mathvariant="normal">7</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="66f756a118b8abe0fa3eab9c9500369f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-4029-2024-ie00004.svg" width="34pt" height="17pt" src="acp-24-4029-2024-ie00004.png"/></svg:svg></span></span> can attract candidate species from the gas phase to the water surface and, thus, accelerate particle growth.</p>