Laboratory for Energy and Nanosciences, Masdar Institute of Science and Technology, Abu Dhabi, United Arab Emirates.
Langmuir. 2013 Feb 19;29(7):2200-6. doi: 10.1021/la3044413. Epub 2013 Feb 5.
Here, processes through which the energy stored in an atomic force microscope cantilever dissipates in the tip-sample interaction are first decoupled qualitatively. A formalism is then presented and shown to allow quantification of fundamental aspects of nanoscale dissipation such as deformation, viscosity, and surface energy hysteresis. Accurate quantification of energy dissipation requires precise calibration of the conversion of the oscillation amplitude from volts to nanometers. In this respect, an experimental methodology is presented that allows such calibration with errors of 3% or less. It is shown how simultaneous decoupling and quantification of dissipative processes and in situ tip radius quantification provide the required information to analyze dependencies of dissipative mechanisms on the relative size of the interacting bodies, that is, tip and surface. When there is chemical affinity, atom-atom dissipative interactions approach the energies of chemical bonds. Such atom-atom interactions are found to be independent of cantilever properties and tip geometry thus implying that they are intensive properties of the system; these interactions prevail in the form of surface energy hysteresis. Viscoelastic dissipation on the other hand is shown to depend on the size of the probe and operational parameters.
首先，定性地解耦了原子力显微镜悬臂梁中储存的能量在针尖-样品相互作用中耗散的过程。然后提出了一种形式主义，并表明它可以量化纳米级耗散的基本方面，如变形、粘度和表面能滞后。准确量化能量耗散需要精确校准将振荡幅度从伏特转换为纳米的转换。在这方面，提出了一种实验方法，允许以 3%或更低的误差进行这种校准。结果表明，同时解耦和量化耗散过程以及原位尖端半径量化提供了分析耗散机制与相互作用体（即尖端和表面）相对大小之间依赖性所需的信息。当存在化学亲和力时，原子-原子耗散相互作用接近化学键的能量。发现这种原子-原子相互作用不依赖于悬臂梁的性质和尖端几何形状，因此意味着它们是系统的强度性质；这些相互作用以表面能滞后的形式存在。另一方面，粘弹性耗散被证明取决于探针的大小和操作参数。
