Size-Resolved Sea Spray Aerosol Particles Studied by Vibrational Sum Frequency Generation
Size-Resolved Sea Spray Aerosol Particles Studied by Vibrational Sum Frequency Generation
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DOI：
10.1021/jp401957k
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发表时间：
2013-08-01
影响因子：
2.9
通讯作者：
Geiger, Franz M.
中科院分区：
文献类型：
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作者：
Ebben, Carlena J.;Ault, Andrew P.;Geiger, Franz M.
我们提出了振动和频产生（SFG）光谱的外表面和内部接口的大小选择的海喷雾气溶胶（SSA）粒子产生的波水槽的斯克里普斯水力实验室。我们的研究结果支持SSA颗粒模型，调用表面活性剂的存在下，在最上层的颗粒层，并表明，表面活性剂丰富的SSA颗粒的烷基链很可能是无序的。具体而言，SFG光谱表明，在整个研究的尺寸范围内，富含表面活性剂的SSA颗粒含有CH振荡器，该振荡器受到分子取向分布的影响，该分子取向分布比与有序和对齐良好的烷基链相关的窄分子分布函数更宽。这一结果是一致的解释，SSA颗粒表面的有机层的渗透性小的反应性和非反应性分子可能是实质性的，允许更多的气体或冷凝相中的反应性和非反应性物种之间的交换比以前认为的。的SFG数据还表明，一个组件模型可能是不够的描述的SSA颗粒的SFG响应。最后，从波浪水槽微层和150 nm大小的SSA颗粒获得的SFG光谱的相似性表明，SFG活性CH振荡器在波浪水槽的最顶层和颗粒的积累模式可能是在类似的化学环境。需要额外的研究活动进行了讨论的背景下提出的结果。
We present vibrational sum frequency generation (SFG) spectra of the external surfaces and the internal interfaces of size-selected sea spray aerosol (SSA) particles generated at the wave flume of the Scripps Hydraulics Laboratory. Our findings support SSA particle models that invoke the presence of surfactants in the topmost particle layer and indicate that the alkyl chains of surfactant-rich SSA particles are likely to be disordered. Specifically, the SFG spectra suggest that across the range of sizes studied, surfactant-rich SSA particles contain CH oscillators that are subject to molecular orientation distributions that are broader than the narrow molecular distribution functions associated with well-ordered and well-aligned alkyl chains. This result is consistent with the interpretation that the permeability of organic layers at SSA particle surfaces to small reactive and nonreactive molecules may be substantial, allowing for much more exchange between reactive and nonreactive species in the gas or the condensed phase than previously thought. The SFG data also suggest that a one-component model is likely to be insufficient for describing the SFG responses of the SSA particles. Finally, the similarity of the SFG spectra obtained from the wave flume microlayer and 150 nm-sized SSA particles suggests that the SFG active CH oscillators in the topmost layer of the wave flume and the particle accumulation mode may be in similar chemical environments. Needs for additional research activities are discussed in the context of the results presented.