Parmentier Evelyne A, Corral Arroyo Pablo, Gruseck Richard, Ban Loren, David Grégory, Signorell Ruth
Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.
J Phys Chem A. 2022 Jul 14;126(27):4456-4464. doi: 10.1021/acs.jpca.2c01370. Epub 2022 Jun 29.
It has recently been reported that reactions can occur faster in microdroplets than in extended condensed matter. The electric charge of droplets has also been suggested as a possible cause of this phenomenon. Here, we investigate the influence of electric charges on the photodegradation of single, optically trapped oleic acid aerosol droplets in the absence of other reactive species. The temporal evolution of the chemical composition and the size of droplets with charge states ranging from 0 to 10 elementary charges were retrieved from Raman spectra and elastic light scattering, respectively. No influence of the droplet charge was observed, either on the chemical composition or on the kinetics. Based on a kinetic multilayer model, we propose a reaction mechanism with the photoexcitation of oleic acid into an excited state, subsequent decay into intermediates and further photoexcitation of intermediates and their decay into nonvolatile and volatile products.
最近有报道称，微滴中的反应可能比在扩展凝聚态物质中发生得更快。液滴的电荷也被认为是这种现象的一个可能原因。在此，我们研究了在不存在其他活性物种的情况下，电荷对单个光学捕获的油酸气溶胶微滴光降解的影响。分别从拉曼光谱和弹性光散射中获取了电荷态从0到10个基本电荷的微滴的化学成分和尺寸随时间的演变。未观察到液滴电荷对化学成分或动力学有影响。基于动力学多层模型，我们提出了一种反应机制，即油酸光激发到激发态，随后衰变为中间体，中间体进一步光激发并衰变为非挥发性和挥发性产物。
