具有排斥相互作用的原子团簇非平衡系统研究  

Studies on a nonequilibrium atomic cluster system with repulsive interactions

作　　者：翟国庆[1,2] 张邦俊[1] 叶高翔[3] 

机构地区：[1]浙江大学环境科学系 [2]浙江大学物理系,杭州310027 [3]浙江大学物理系

出　　处：《物理学报》2005年第4期1557-1563,共7页Acta Physica Sinica

基　　金：国家自然科学基金 (批准号 :10 2 0 40 18;10 1740 63 )资助的课题~~

摘　　要：在无格点基底表面建立了存在排斥相互作用的原子团簇凝聚及扩散模型 ,对沉积在均匀带电硅油基底表面的银原子凝聚过程进行了研究 .结果表明 :当沉积原子凝聚成稳定的原子团簇后 ,由于带同种电荷 ,团簇之间存在库仑排斥作用 ,团簇数密度随时间呈指数形式衰减 ,衰减时间常数为Oa;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 .停止沉积后初期 ,H≈Oa,然后随着扩散时间的增加 ,H逐渐趋于零 ;随着液体基底黏滞系数增加 ,摩擦力增大 ,H逐渐减小 ,摩擦力与H基本满足线性关系 ,其斜率为 0 10± 0 0 1;原子团簇开始带电的临界半径r1 与沉积原子吸收电子的亲和能大小密切相关 .研究表明 :H与Oa 均随r1 增加而缓慢增大 ,斜率分别为 1 2± 0 3s- 1 μm- 1 和 1 6± 0 6s- 1 μm- 1 .模拟结果与实验值基本一致 .A simulation model for diffusion and aggregation of atomic clusters with repulsive interactions on nonlattiee substrates is established, and the aggregation process of the silver atoms on charged silicone oil surfaces has been studied. It was found that after the stable atomic clusters form, due to the repulsive interaction among the clusters, the number density of the atomic clusters decays with time exponentially and the time constant is O-a ; statistically, the relative speed V between two clusters increases linearly with their distance L according to V = HL, where the constant H approximate to O-a after deposition and then approaches zero with Lime. With the increase of the viscosity coefficient of liquid substrates, the friction force increases and H decreases. A linear relation between the friction force and H is found with the slope k approximate to 0.10 +/- 0.01. We show that the critical radius r(1) of the clusters, above which the atomic clusters start to carry charges, is related nearly to the atomic affinity, i.e., the energy needed for the cluster to carry an extra electron. It is found that H and O-a increase slowly with r(1) and their slopes are 1.2 +/- 0.3 s(-1) mu m(-1) and 1.6 +/- 0.6 s(-1) mu m(-1) respectively. Our simulation results are in agreement with the previous experimental findings.

关 键 词：排斥相互作用 原子团簇 非平衡系统 扩散模型 

分 类 号：O561[理学—原子与分子物理]