原子力显微镜引力域成像的驱动频率优化研究

Optimal driving frequency for attractive regime tapping mode atomic force microscope

探针的驱动频率是决定轻敲模式原子力显微镜工作域的重要因素之一。高于共振频率的驱动频率可明显促进探针工作在引力域。本文研究了驱动频率对探针在两个工作区域即引力域和斥力域之间进行转换的重要影响。采用数值仿真的方法针对不同的驱动频率研究了振幅距离曲线和行扫描曲线。结果证明不同的驱动频率对探针工作在引力域的促进作用不同,当选择高于共振频率且探针振幅下降到自由状态下共振振幅的30%时所对应的驱动频率附近,此时的驱动频率对引力域成像促进效果最好。

The driving frequency is a significant parameter to determine the working regime in tapping mode atomic force microscope.The working regime can be evidently promoted by adjusting the driving frequency above the resonance.The comprehensive study about the effects of driving frequencies above resonance on the transition between two regimes is described in this article.Amplitudeseparation curves and line scans over a step are performed in numerical calculations for various driving frequencies.The results show that different driving frequencies promote attractive regime respectively and those above resonance and whose oscillating amplitudes drop down to about 30% of the free amplitude at resonance provide the best stability for attractive regime.