Three-Dimensional Atomic Force Microscopy: Interaction Force Vector by Direct Observation of Tip Trajectory
Three-Dimensional Atomic Force Microscopy: Interaction Force Vector by Direct Observation of Tip Trajectory
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DOI：
10.1021/nl403423p
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发表时间：
2013-11-01
期刊：
影响因子：
10.8
通讯作者：
King, Gavin M.
中科院分区：
文献类型：
--
作者：
Sigdel, Krishna P.;Grayer, Justin S.;King, Gavin M.
强大的三维原子力显微镜（AFM）的前景在纳米科学领域具有重大前景。然而，在传统的 AFM 中，尖端样本相互作用力矢量无法直接获取。我们将聚焦激光直接从 AFM 尖端顶点散射，以快速、精确地测量三维空间中的攻丝尖端轨迹。该数据还产生三维悬臂弹簧常数、有效质量，从而通过牛顿第二定律产生尖端样本相互作用力分量。当硅尖端间歇性地接触水溶液中的玻璃基板时，在常见的敲击模式条件下观察到代表 49·20 A 的显着侧向力和法向力的 13% (F-z = 152 +/- 17 pN)；结果，力矢量的方向倾斜得比预期的要大得多。当处理脂质双层表面时，力分量的行为与在玻璃上观察到的显着不同。这归因于脂质膜的横向流动性及其弹性特性。直接访问相互作用分量 F 和 Fz 提供了更完整的尖端动力学视图，该动力学是力显微镜操作的基础，并且可以形成多种条件下的三维 AFM 的基础。
The prospect of a robust three-dimensional atomic force microscope (AFM) holds significant promise in nanoscience. Yet, in conventional AFM, the tip sample interaction force vector is not directly accessible. We scatter a focused laser directly off an AFM tip apex to rapidly and precisely measure the tapping tip trajectory in three-dimensional space. This data also yields three-dimensional cantilever spring constants, effective masses, and hence, the tip sample interaction force components via Newton's second law. Significant lateral forces representing 49 20 A and 13% of the normal force (F-z = 152 +/- 17 pN) were observed in common tapping mode conditions as a silicon tip intermittently contacted a glass substrate in aqueous solution; as a consequence, the direction of the force vector tilted considerably more than expected. When addressing the surface of a lipid bilayer, the behavior of the force components differed significantly from that observed on glass. This is attributed to the lateral mobility of the lipid membrane coupled with its elastic properties. Direct access to interaction components F, and Fz provides a more complete view of tip dynamics that underlie force microscope operation and can form the foundation of a three-dimensional AFM in a plurality of conditions.