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105/12/20 14:00 中央大學環境工程研究所蕭大智助理教授 演講
演講公告
張貼人：網站管理員 ╱ 公告日期：2016-12-14演 講 公 告
主講人：蕭大智 助理教授
地點：中央大學科學一館S-325教室
摘要：
講題：Aqueous Film Formation on Irregularly Shaped Inorganic Nanoparticles before Deliquescence
主講人：蕭大智 助理教授
中央大學環境工程研究所
時間：12月20日（星期二）下午2點
地點：中央大學科學一館S-325教室
摘要：
A hygroscopic tandem differential mobility analyzer (H-TDMA) and a hygroscopic coupled DMA and aerosol particle mass (H-DMA-APM) were coupled to examine water film formation and the deliquescence behavior of inorganic nanoparticles. The two systems complement each other because H-DMA-APM measures mass change, while H-TDMA measures diameter (volume) change of nanoparticles upon water uptake. The former mass change was in particular more capable to discern minute particle phase changes than the latter size change at moderate RHs. The mass and diameter changes were used to derive the particle effective density for evaluation of water film formation on the nanoparticle surface before and after deliquescence transition. The measurements further showed that approximately 3–5 and 12–20 monolayers of water molecules formed on the respective surface of 50- and 100-nm sodium chloride and ammonium sulfate aerosols before deliquescence relative humidity (DRH). These findings support the physical basis of the coated-surface model by Russell and Ming (2002), and suggest that the phase transition of inorganic nanoparticles near deliquescence is a gradual process instead of an abrupt change. This phenomenon changed the surface tension ratio and surface energy values, thus confirming the explanation by (Biskos et al. 2006a; Biskos et al. 2006c) that the DRH of nanoparticles increases as the particle size decreases. This is the first direct observation of nanoparticle deliquescence phase transition using the H-DMA–APM system, and the detailed characterization of water film formation on inorganic nanoparticles is feasible with the presented measurement systems.
最後修改時間：2016-12-14 PM 5:19
