Kurtén Theo, Bonn Boris, Vehkamäki Hanna, Kulmala Markku
Department of Physical Sciences, University of Helsinki, P. O. Box 64, FIN-00014 Helsinki, Finland.
J Phys Chem A. 2007 May 3;111(17):3394-401. doi: 10.1021/jp067817k. Epub 2007 Apr 10.
We have postulated a mechanism for the reaction of sulfuric acid with stabilized Criegee intermediates (sCIs). We have computed Gibbs free energies for the reaction of sulfuric acid with two biogenic sCIs and three smaller model species. We have also calculated Gibbs free energies for two competing sink reactions. Due to the large size of the biogenic sCIs, the computations have been performed at the relatively modest B3LYP/6-31G(d,p) and B3LYP/6-311+G(2d,p) levels. However, single-point RI-CC2/def2-QZVPP calculations for the (CH3)(2)COO model species are in good agreement with the B3LYP results. The reaction is found to be strongly exothermic for all studied species. Activation barrier calculations on the (CH3)(2)COO model species further indicate that the reaction with sulfuric acid may proceed significantly faster than the sink reaction with water. If the same applies to the biogenic sCIs, the proposed reactions could account for some part of the organically assisted new particle formation events observed in the atmosphere.
我们推测了硫酸与稳定的克里吉中间体（sCIs）反应的机理。我们计算了硫酸与两种生物源sCIs以及三种较小模型物种反应的吉布斯自由能。我们还计算了两个竞争消除反应的吉布斯自由能。由于生物源sCIs的尺寸较大，计算是在相对适中的B3LYP/6 - 31G(d,p)和B3LYP/6 - 311+G(2d,p)水平上进行的。然而，对(CH3)(2)COO模型物种进行的单点RI - CC2/def2 - QZVPP计算与B3LYP结果吻合良好。发现该反应对所有研究的物种都是强烈放热的。对(CH3)(2)COO模型物种的活化能垒计算进一步表明，与硫酸的反应可能比与水的消除反应进行得快得多。如果这同样适用于生物源sCIs，那么所提出的反应可能解释了在大气中观察到的部分有机辅助新粒子形成事件。
