In situ analysis of the bulk and surface chemical compositions of organic aerosol particles.
In situ analysis of the bulk and surface chemical compositions of organic aerosol particles.
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DOI：
10.1038/s42004-022-00674-8
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发表时间：
2022-04-29
影响因子：
5.9
通讯作者：
Rao, Yi
中科院分区：
文献类型：
--
作者：
Qian, Yuqin;Brown, Jesse B.;Huang-Fu, Zhi-Chao;Zhang, Tong;Wang, Hui;Wang, ShanYi;Dadap, Jerry, I;Rao, Yi
了解颗粒物的化学和物理性质是一个重要的科学，工程和医学问题，对空气质量，人类健康和环境化学至关重要。特别令人感兴趣的是漂浮在空气中的气溶胶颗粒，用于室内病毒传播和室外大气化学。生物和有机气溶胶颗粒在空气中的生长与气溶胶颗粒表面和颗粒内相的化学结构及其在气相中的反应密切相关。然而，在空气中的气溶胶颗粒表面的化学结构的直接测量是缺乏的。在这里，我们展示了在原位表面特定的振动和频散射（VSFS），直接识别在气溶胶颗粒表面的分子的化学结构。此外，我们的设置允许我们同时探测粒子相中的超拉曼散射（HRS）光谱。我们研究了偏振VSFS光谱丙酸在气溶胶颗粒表面和颗粒体。更重要的是，丙酸到气溶胶颗粒上的表面吸附自由能被发现比在空气/水界面处的吸附自由能更小。这些结果挑战了长期存在的假设，即在空气/水界面的分子行为是相同的气溶胶颗粒表面。我们的方法为揭示大气中二次有机气溶胶形成过程中的表面成分和化学老化以及室内和室外病毒气溶胶颗粒的化学分析开辟了一条新途径。探测有机气溶胶颗粒的化学成分对于了解其生长机制至关重要，但缺乏直接探测气溶胶颗粒表面化学物种的方法。在这里，在原位表面特定的振动和频散射光谱显示，直接识别存在于有机气溶胶颗粒表面上的分子的化学结构。
Understanding the chemical and physical properties of particles is an important scientific, engineering, and medical issue that is crucial to air quality, human health, and environmental chemistry. Of special interest are aerosol particles floating in the air for both indoor virus transmission and outdoor atmospheric chemistry. The growth of bio- and organic-aerosol particles in the air is intimately correlated with chemical structures and their reactions in the gas phase at aerosol particle surfaces and in-particle phases. However, direct measurements of chemical structures at aerosol particle surfaces in the air are lacking. Here we demonstrate in situ surface-specific vibrational sum frequency scattering (VSFS) to directly identify chemical structures of molecules at aerosol particle surfaces. Furthermore, our setup allows us to simultaneously probe hyper-Raman scattering (HRS) spectra in the particle phase. We examined polarized VSFS spectra of propionic acid at aerosol particle surfaces and in particle bulk. More importantly, the surface adsorption free energy of propionic acid onto aerosol particles was found to be less negative than that at the air/water interface. These results challenge the long-standing hypothesis that molecular behaviors at the air/water interface are the same as those at aerosol particle surfaces. Our approach opens a new avenue in revealing surface compositions and chemical aging in the formation of secondary organic aerosols in the atmosphere as well as chemical analysis of indoor and outdoor viral aerosol particles. Probing the chemical compositions of organic aerosol particles is crucial for understanding their growth mechanisms, but methods to directly probe chemical species at aerosol particle surfaces are lacking. Here, in situ surface-specific vibrational sum frequency scattering spectroscopy is shown to directly identify the chemical structures of molecules present on organic aerosol particle surfaces.
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影响因子：
3.3
作者：
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通讯作者：
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影响因子：
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