Coagulation of nanoparticles in a plasma.
Coagulation of nanoparticles in a plasma.
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DOI：
10.1103/physreve.79.026408
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发表时间：
2009-02
期刊：
影响因子：
--
通讯作者：
L. Ravi;S. Girshick
中科院分区：
文献类型：
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作者：
L. Ravi;S. Girshick
通过建立纳米粒子-等离子体系统时空演化的详细数值模型，研究了纳米粒子在低压射频等离子体中的凝聚过程。模拟结果表明，在这类体系中发生任何程度的凝聚都需要存在两个效应：第一，气相成核不限于短暂的爆发，而是在充分没有纳米颗粒的区域继续；第二，中性颗粒和负电荷纳米颗粒之间碰撞的凝聚系数因中性颗粒中诱导的镜像电势而增加。考虑到这些影响，凝聚被预测为非常小(直径约1或2 nm)的中性粒子与捕获在等离子体中的较大的负电荷粒子之间的凝聚。当纳米粒子云在等离子体上的扩散抑制了气相成核时，凝聚就停止了。
Coagulation of nanoparticles in a low-pressure radio frequency plasma was studied by means of a detailed numerical model for the spatiotemporal evolution of the nanoparticle-plasma system. Simulation results indicate that the occurrence of coagulation to any significant degree in such systems requires the existence of two effects: first, gas-phase nucleation is not limited to a brief burst, but rather continues in regions that are sufficiently free of nanoparticles; and second, coagulation coefficients for collisions between neutral and negatively charged nanoparticles are enhanced by the image potential induced in the neutral particle. Accounting for these effects, coagulation is predicted to be dominated by coagulation between very small (approximately 1 or 2 nm in diameter) neutral particles and larger negatively charged particles that are trapped in the plasma. Coagulation ceases when the spreading of the nanoparticle cloud across the plasma quenches gas-phase nucleation.