Butt Hans-Jürgen, Franz Volker
Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Sep;66(3 Pt 1):031601. doi: 10.1103/PhysRevE.66.031601. Epub 2002 Sep 5.
In atomic force microscope studies of molecular thin films, a defined jump of the tip through the film is often observed once a certain threshold force has been exceeded. Here, we present a theory to describe this film rupture and to relate microscopic parameters to measurable quantities. We assume that the tip has to overcome an activation energy before the film ruptures. A universal relation between the force dependence of the activation energy and the approaching velocity of the tip is derived. Two complementary models for calculating the activation energy are presented: a continuum nucleation model and a discrete molecular model. Both models predict a narrow distribution of yield forces in agreement with experimental results.
在分子薄膜的原子力显微镜研究中，一旦超过某个阈值力，通常会观察到针尖穿过薄膜的明确跳跃。在此，我们提出一种理论来描述这种薄膜破裂，并将微观参数与可测量量联系起来。我们假设在薄膜破裂之前，针尖必须克服一个活化能。推导出了活化能的力依赖性与针尖接近速度之间的通用关系。提出了两种计算活化能的互补模型：连续形核模型和离散分子模型。这两种模型都预测屈服力的分布很窄，与实验结果一致。
