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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Gas uptake and chemical aging of semisolid organic aerosol particles
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Gas uptake and chemical aging of semisolid organic aerosol particles

机译：半固体有机气溶胶颗粒的气体吸收和化学老化

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摘要

Organic substances can adopt an amorphous solid or semisolid state, influencing the rate of heterogeneous reactions and multi phase processes in atmospheric aerosols. Here we demonstrate how molecular diffusion in the condensed phase affects the gas uptake and chemical transformation of semisolid organic particles. Flow tube experiments show that the ozone uptake and oxidative aging of amorphous protein is kinetically limited by bulk diffusion. The reactive gas uptake exhibits a pronounced increase with rela tive humidity, which can be explained by a decrease of viscosity and increase of diffusivity due to hygroscopic water uptake trans forming the amorphous organic matrix from a glassy to a semi solid state (moisture-induced phase transition). The reaction rate depends on the condensed phase diffusion coefficients of both the oxidant and the organic reactant molecules, which can be de scribed by a kinetic multilayer flux model but not by the traditional resistor model approach of multiphase chemistry. The chemical life time of reactive compounds in atmospheric particles can increase from seconds to days as the rate of diffusion in semisolid phases can decrease by multiple orders of magnitude in response to low temperature or low relative humidity. The findings demonstrate that the occurrence and properties of amorphous semisolid phases challenge traditional views and require advanced formalisms for the description of organic particle formation and transformation in atmospheric models of aerosol effects on air quality, public health, and climate.
机译：有机物质可以采用非晶态固态或半固态，从而影响大气气溶胶中的异相反应和多相过程的速率。在这里，我们证明了冷凝相中的分子扩散如何影响半固态有机颗粒的气体吸收和化学转化。流量管实验表明，无定形蛋白质的臭氧吸收和氧化老化在动力学上受到整体扩散的限制。反应性气体的吸收量随相对湿度的增加而显着增加，这可以用吸湿性吸水剂将非晶态有机基质从玻璃态转变为半固态（水分诱导相）引起的粘度降低和扩散率提高来解释。过渡）。反应速率取决于氧化剂和有机反应物分子的冷凝相扩散系数，这可以通过动力学多层通量模型来描述，而不能通过传统的多相化学的电阻器模型方法来描述。由于响应于低温或低相对湿度，半固态中的扩散速率可以降低多个数量级，因此大气颗粒中反应性化合物的化学寿命可以从数秒增加到几天。研究结果表明，非晶半固体相的出现和性质挑战了传统观点，并需要先进的形式主义来描述气溶胶对空气质量，公共卫生和气候的大气模型中有机颗粒的形成和转化。

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