用扫描隧道显微镜测量局域功函数

用扫描隧道显微镜在Cu（111）-Au和Pt（111）-Ag表面上对局域功函数进行了测量．在扫描的同时通过测量隧道电流对针尖样品间距离变化的响应，可以在得到扫描隧道显微镜（STM）图的同时得到功函数图．用这种方法，成功地观察到Au，Ag覆盖层与Cu，Pt衬底间的功函数的差别．结果表明：Au覆盖层的功函数介于Cu（111）和Au（111）的功函数之间，这与其它方法的结果一致．在Pt（111）-Ag表面观察到了局域功函数随覆盖层厚度的变化．本工作表明：扫描隧道显微镜在研究功函数与表面结构的关系方面是十分有用的；用测量局域功函数的方法还可以区分表面不同种的物质 关键词：

LOCAL WORK FUNCTION MEASURED WITH SCANNING TUNNELING MICROSCOPY

In the present paper we report local work function measurements on the Cu(111)-Au and Pt(111)-Ag surfaces using scanning tunneling microscopy (STM).By measuring the response of tunneling current to the variation of the tunneling gap distance a work function image can be obtained simultaneously with a topographic STM image. By means of this technique,we are able to detect the difference between the local work functions of the overlayer and the substrate in both Cu(111)-Au and Pt(111)-Ag cases.Our results show that the local work function of the Au overlayer is between those of Au(111) and Cu(111) surfaces,supporting the results obtained with other techniques. In the case of the Pt(111)-Ag surface the local work function depends on the local thickness of the Ag overlayer.