Direct Surface Tension Measurements of Individual Sub-Micrometer Particles Using Atomic Force Microscopy
Direct Surface Tension Measurements of Individual Sub-Micrometer Particles Using Atomic Force Microscopy
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DOI：
10.1021/acs.jpca.7b04041
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发表时间：
2017-11-02
影响因子：
2.9
通讯作者：
Tivanski, Alexei V.
中科院分区：
文献类型：
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作者：
Lee, Hansol D.;Estillore, Armando D.;Tivanski, Alexei V.
由于海洋气溶胶（SSA）在整个地球大气中的大量集中，因此了解它们对气候和环境的作用具有很大的意义。尽管具有重要的基础意义，但与SSA相关的亚微米颗粒的直接表面张力测量很少，这主要是由于它们的体积非常小。本文使用原子力显微镜（AFM）直接测量环境温度和相对湿度（RH）变化下单个亚微米SSA颗粒模拟物的表面张力。具体来说，我们探索了与大气相关的和基本重要的模型系统，包括电解质盐、二羧酸和糖作为单一成分和混合物。我们的结果表明，单颗粒表面张力取决于相对湿度或溶质摩尔百分比和化学成分。此外，对于粘度为100pa s或低于100pa s的液滴，或在相应的相对湿度下，我们发现在重叠浓度范围内，AFM单颗粒和体溶液表面张力测量结果吻合良好。因此，使用原子力显微镜对单个颗粒的直接表面张力测量显示，在广泛的化学系统中，与以前报道的相比，它是相对湿度、溶质摩尔百分比和粘度的函数。
Understanding the role of sea spray aerosol (SSA) on climate and the environment is of great interest due to their high number concentration throughout the Earth's atmosphere. Despite being of fundamental importance, direct surface tension measurements of SSA relevant sub-micrometer particles are rare, largely due to their extremely small volumes. Herein, atomic force microscopy (AFM) is used to directly measure the surface tension of individual sub-micrometer SSA particle mimics at ambient temperature and varying relative humidity (RH). Specifically, we probed both atmospherically relevant and fundamentally important model systems including electrolyte salts, dicarboxylic acids, and saccharides as single components and mixtures. Our results show that the single particle surface tension depends on RH or solute mole percentage and chemical composition. Moreover, for liquid droplets at and below 100 Pa s in viscosity, or at corresponding RH, we show good agreement between the AFM single particle and the bulk solution surface tension measurements at overlapping concentration ranges. Thus, direct surface tension measurements of individual particles using AFM is shown over a wide range of chemical systems as a function of RH, solute mole percentage, and viscosity than previously reported.