Na原子在Si(111)-(7×7)表面的吸附:从二维原子气到纳米团簇阵列

Na adsorption on the Si (111)-(7×7) surface:from a two dimensional gas to magic clusters

作者利用扫描隧道显微镜 (STM)详细研究了室温下Na原子在Si(111) (7× 7)表面的吸附 .对STM图像及功函数变化的分析表明 ,当Na原子覆盖度小于临界覆盖度 (0 .0 8ML)时 ,Na原子具有类气态的性质并可以在一个吸附能阱中快速移动 .从STM图像可看出这种移动导致的对比度调制 .在临界覆盖度以上 ,Na原子自组装形成团簇阵列 .第一原理模拟计算的结果与作者的实验结论很好吻合 .

We have performed a detailed investigation of Na adsorption on the Si(111)-(7×7) surface at room temperature by scanning tunneling microscopy (STM). By analyzing the images and the work function change, we propose a new scheme for this well-studied system. Below the critical coverage of 0.08ML, the STM images show intriguing contrast modulation, which indicates that Na atoms move freely in the attraction basin, behaving as a gaslike phase. Above the critical coverage, Na clusters emerge and form a self-assembled array. First-principles theoretical simulations agree perfectly with our experiment.