振动模式扫描极化力显微镜及其应用

Vibrating mode scanning polarization force microscopy and its applications

振动模式扫描极化力显微镜采用一种新的扫描探针显微成像方式 ,它可以在极化力介导的非接触方式和轻敲方式之间自由切换。在极化力介导的非接触方式中 ,极化力叠加在范德华力上 ,克服了一般的原子力显微镜(AFM)非接触模式中因成像力程太短而不容易稳定的缺点 ;通过调节针尖的高度 ,从极化力介导的非接触方式进入到极化力介导的轻敲方式 ,又能部分消除AFM轻敲模式中毛细力的干扰 ,还可以用比AFM轻敲模式中最小稳定成像力更小的力进行成像。针尖的高度可以通过调节Asp(Amplitudesetpoint)或插入扫描高度参数 (liftscanheight)来控制 ,这一方法简单易行。利用这一模式对胶体金颗粒和DNA的高度进行测量 ,在一定程度上证明了轻敲模式中针尖压力的确会造成柔软生物样品的变形。

Vibrating mode scanning polarization force microscopy (VSPFM) has been developed as a new kind of imaging mode and its application on the measurement of the heights of soft samples were reported in this paper. In VSPFM, imaging can be changed from non contact mode to tapping mode directly, both of which are coupled with polarization forces. In non contact imaging on rough surface, VSPFM is more stable than conventional non contact mode AFM since polarization forces have a longer range than van der Waals forces. In VSPFM tapping mode, very small imaging force could be achieved by adjusting the amplitude setpoint ( A sp ) near the joint point between non contact and tapping, and adhesive forces were partly eliminated. The height of the tip over the surface can be determined by changing A sp or lift scan height. The measurement of heights of colloidal gold and DNA by VSPFM proved that tip pressure could cause deformation on soft biological samples in normal tapping mode.