Effects of dicarboxylic acid coating on the optical properties of soot.
Effects of dicarboxylic acid coating on the optical properties of soot.
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DOI：
10.1039/b904129j
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发表时间：
2009-09
期刊：
影响因子：
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通讯作者：
H. Xue;A. Khalizov;Lin Wang;Jun Zheng;Renyi Zhang
中科院分区：
文献类型：
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作者：
H. Xue;A. Khalizov;Lin Wang;Jun Zheng;Renyi Zhang
煤烟是大气气溶胶的主要成分，负责吸收可见的太阳辐射。煤烟与透明材料的内部混合可以增强其吸收和散射光的能力，从而使煤烟在气候强迫中发挥更大的作用。我们已经调查了吸收和散射的可见光（532 nm）的煤烟气溶胶内部混合琥珀酸和谷氨酸使用的组合腔衰荡光谱仪和积分浊度计。火焰产生的烟尘气溶胶进行了测量，具有良好的表征形态和混合状态的粒径范围从155到320 nm。烟灰聚集体上的二羧酸的薄涂层（质量分数为0.1-0.4）显著增强光散射（高达3.8倍）和轻微的光吸收（小于1.2倍）。使涂覆的烟灰气溶胶循环通过高相对湿度（加湿至90%RH，然后干燥至5%RH）促进了与谷氨酸内部混合的烟灰的光吸收和散射的进一步增加，但不促进与琥珀酸混合的烟灰的光吸收和散射的进一步增加。谷氨酸对光吸收和散射的较大影响是由涂层材料诱导的烟灰聚集体的不可逆重组引起的。我们的研究结果表明，增强的光学性能的烟灰透明涂层是密切相关的涂层材料的能力，改变烟灰聚集体的形态。
Soot is a major component of atmospheric aerosols responsible for absorption of visible solar radiation. Internal mixing of soot with transparent materials can enhance its ability to absorb and scatter light, resulting in a larger role of soot in climate forcing. We have investigated the absorption and scattering of visible light (532 nm) by soot aerosol internally mixed with succinic and glutaric acids using a combination of a cavity ring-down spectrometer and an integrating nephelometer. The measurements were performed for flame-generated soot aerosol with well-characterized morphology and mixing state in the particle size range from 155 to 320 nm. Thin coatings of dicarboxylic acids on soot aggregates (with a mass fraction of 0.1-0.4) enhance significantly light scattering (up to 3.8 fold) and slightly light absorption (less than 1.2 fold). Cycling the coated soot aerosol through high relative humidity (humidified to 90% RH and then dried to 5% RH) promotes further increase in light absorption and scattering for soot internally mixed with glutaric acid, but not for soot mixed with succinic acid. The larger effect of glutaric acid on light absorption and scattering is caused by the irreversible restructuring of soot aggregates induced by the coating material. Our results indicate that the enhancement in the optical properties of soot by transparent coatings is strongly related to the ability of the coating materials to change the morphology of soot aggregates.