NC-AFM Imaging of Adsorbed Molecules

Abstract

High-resolution imaging of organic materials is of great importance in surface chemistry and physics. Although scanning tunneling microscopy (STM) has sufficient resolution for imaging conductive samples at an atomic scale, an STM tip often has to penetrate poorly conducting samples such as thick organic films to sustain a tunneling current [1,2]. Deformation and damage of sample surfaces and even the motion of isolated molecules then occur during scanning. On the other hand, atomic force microscopy (AFM) offers the possibility of imaging nonconductive samples. Contact or tapping AFM cannot avoid damage to both the tip apex and the sample surface due to a large loading force, and true atomic resolution has not therefore been achieved. Furthermore, contact AFM sometimes causes local deformation of soft materials and the motion of molecules adsorbed on substrates [3],4].