带电液体基底表面银原子的凝聚和扩散行为

Diffusion and aggregation behaviors of silver atoms on charged liquid substrates

研究了沉积在带电液体基底 (硅油 )表面的银原子的凝聚以及扩散行为 .先采用热阴极电子发射方法使液体基底表面均匀带电 ,然后用蒸发沉积方法将银原子沉积到带电的液体基底表面 .实验发现 :被沉积的银原子首先凝聚成直径约为 1 2 μm的准圆形团簇 ,然后由于库仑排斥力作用而相互离散 ,所有团簇均向基底的四周边缘漂移 ;基底表面的团簇数密度n随时间t指数衰减 ,衰减时间常量Of≈ 1 1× 10 - 4s- 1 ;两团簇相互离散的相对平均速率V与它们之间的相对距离L在统计意义上成正比 ,即V =HL ,其中沉积刚结束时常量H≈ 2 9× 10 - 4s- 1 ,然后随扩散时间t而逐渐趋于零 .分析表明 :由于带电银原子团簇的扩散运动 ,使基底表面的电荷重新分布 。

Diffusion and aggregation behaviors of silver atoms deposited on charged liquid substrates (silicone oil) are studied.The substrates are charged before deposition by a thermal cathode emission current,then silver atoms are deposited on the charged substrates by thermal evaporation.The experiment shows that the deposited silver atoms aggregate first and compact clusters with the average diameter of 1.2μm form.Then the clusters separate each other due to the repulsive Coulomb interaction and drift towards the edge of the substrate;an exponential decay of the cluster number density n with time t is observed and the corresponding time constant is O f≈1 1×10 -4 s -1 ;statistically,the relative speed V between two clusters increases linearly with their distance L according to V=HL , where the constant H =2 9×10 -4 s -1 after deposition and approaches zero with time.Our analysis shows that,due to the diffusion of the charged clusters,the charge density on the substrate rearranges and gradually the electric field on the substrate tend to be homogeneous.