原子力显微术轻敲模式中探针样品接触过程及相位衬度研究

借助简单的有阻尼受迫振子模型，研究了原子力显微术轻敲模式中探针与样品接触时间t_c、样品的表面形变D_z和相位衬度对探针设置高度z_c及样品杨氏模量E_s的依赖关系.结果发现,t_c与D_z均随E_s及z_c的增大而减小，同时探针与样品作用过程伴随很小的能量耗散.对轻敲过程中相移量φ的研究表明，E_s较大的样品有较小的φ，且φ随 关键词： 原子力显微术 轻敲模式 相位衬度

Study of tip-sample contact process and phase contrast in tapping mode atomic force microscopy

The tapping-mode atomic force microscope (TM-AFM) is a very useful tool to investigate the morphology and the physical properties of sample surface. The tip-sample contact process and phase contrast of TM-AFM is studied by numerical simulation. The cantilever-tip ensemble is simply modeled as a damped harmonic oscillator driven by an actuator. The effects of tip-sample distance z_c and the Young modulus of sample E_s on the contact time between the tip and sample t_c, the deformation of the sample surface D_z and the contrast of phase image have been investigated. The results show that both t_c and D_z decrease with increasing E_s or z_c. A little amount of energy dissipation can occur when the tip is tapping on the sample. Moreover, when z_c is fixed, the phase shift of the sample with large E_s is found more remarkable than that with small E_s. The experimental observation of phase image performed on Au film dispersed with Au clusters supports the simulation results.