奈米固體微粒是造成空氣污染的重要來源，這些微粒由於粒徑小且重量輕，可在大氣中飄浮甚久，降低能見度，甚至危害人體健康。然而迄今在帶電微粒上之核凝機構以及理論仍未充份了解；對於實驗值與理論值之比較也甚缺乏。本研究以流動型雲霧室來探討水蒸汽以及正丁醇蒸汽在SiO2以及TiO2帶電微粒上的核凝現象。在雲霧室中過飽和蒸汽以微粒為凝結核，冷凝長大成小液滴，因重力而去除。藉由量測去除效率隨過飽和度之變化配合理論分析求出臨界過飽和度。

由實驗結果的可以得知，在直徑15nm以上的次微米微粒上，水蒸氣發生非均勻相核凝之的臨界過飽和度並不會隨著微粒是否帶電正或負電荷而有所影響。另外本研究引進電噴霧系統生產奈米微粒，然而卻因為系統設計不良導致這套生產裝置沒有達到預期的效果。

Nano solid particles are one of important contributors to air pollution. These particles have long airborne lifetimes largely responsible for reduced visibility through urban air and possess potential health hazard. The physical processes involved in the heterogeneous nucleation of supersaturation vapor on of charge particles are not fully understood.

A systematic study on the heterogeneous nucleation of vapor on TiO2 and SiO2 charged particles is proposed employing a flow cloud chamber (FCC). Supersaturated water or n-butanol vapor condenses onto the particles, which grow up to larger sizes and settle out with appreciable velocities. The critical supersaturation required for a nucleation rate of one on a particle is obtained from the measurement of the removal efficiency a function of supersaturation in conjuction with a theoretical analysis.

The experimental results show that there is no charge effect and sign preference on the critical supersaturation for SiO2 particles with a diameter larger than 15nm. This experimental employ a new nanoparticle generation system, i.e. electrospray system, to product nanoparticles. Because of defects in the system design, the electrospray system didn’t work as expected.

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