原子力显微镜针尖与样品间的材料转移

研究氮化硅针尖在十八烷基三甲氧基硅烷 (OTE) /云母表面的修饰过程。使用原子力 /摩擦力显微镜 ,以云母作为参考样品 ,研究了针尖在样品表面的修饰效应和修饰后针尖的清洁过程 ,并考察了湿度和载荷对针尖修饰效应的影响。修饰过程不是一个渐进的过程 ,在最初几次摩擦扫描中修饰较快 ,然后在 10～ 2 0次扫描后达到平衡态。在 OTE/云母表面修饰后的针尖在云母表面的摩擦力信号比修饰前针尖在云母表面的摩擦力信号小 ,并且大部分吸附在针尖表面的 OTE分子在云母表面的前 10次扫描中就被磨掉。相对湿度对针尖的修饰效应影响不大。在研究不同样品的摩擦性能时 ,尽量使用清洁针尖 ,并使用摩擦性能稳定的参考样品 (如云母 )来检测针尖的表面状态

Material transfer from sample surfaces to the tips of atomic force microscopes

Modification and cleaning of the silicon nitride tips of atomic force/friction force microscopy (AFM/FFM) on the surface of octadecyltrimethoxysilane (OTE/mica) were studied with a reference sample of mica. The effect of relative humidity and load on the modification was also tested. The experimental results showed that the modification process was not gradual but occurred quickly during the first several friction scans and that the tip condition readed steady state during the following 10~20 friction scans. The tips modified on the surface of OTE/mica had lower friction and adhesion on the mica surface than the unmodified tips. Most of the adsorbed molecules on the tip surface were cleaned within the first ten friction scans on the mica surface. The tip modification was weakly dependent on the humidity. The load had a strong effect on the tip modification. Therefore, clean tips should be used to study the tribological properties of different samples, and the samples, e.g. mica, with stable tribological properties should be used to investigate the state of the tip surface.