扫描隧道显微镜中场蒸发过程的理论分析

A THEORETICAL ANALYSIS OF THE FIELD EVAPORATION IN THE CONFIGURATION OF SCANNING TUNNELING MICROSCOPE

从电热动力学（Ｅｌｅｃｔｒｏｔｈｅｒｍｏｄｙｎａｍｉｃｓ）角度出发，分析了扫描隧道显微镜（ＳＴＭ）中场蒸发过程．引入了一个有效结合能，并推导得到了ＳＴＭ中的蒸发场强计算公式．用该公式计算得到了与实验一致的金离子的蒸发场强．同时发现传统的电荷交换模型与成象势垒模型，由于它们要求被蒸发原子完全电离并被蒸发到无穷远处，因而对ＳＴＭ计算的蒸发场强偏高．

Abstract An electrothermodynamic analysis of field evaporation in the configuration of scanning tunneling microscope(STM) has been performed. By introduction of an effective binding energy, a formula for the evaporation field in STM has been constructed. The calculated evaporation field for Au -1 , for the first time to our knowledge, agrees well with experiment. On the other hand it was found that the classic charge exchange model and image hump model yield very high evaporation field because they require that the adatoms be fully ionized and evaporated to infinity.