Studies of the mechanics and friction of nanometer-scale materials.

摘要

An atomic force microscope (AFM) was provided with an interface designed for advanced manipulation studies. This instrument, called the Nanomanipulator, provides the operator the ability to "manually" manipulate nanometer-scale objects on surfaces. In addition, the topographical AFM data is presented in both a highly sophisticated graphical form as well as through force feedback, creating a very intuitive way of interacting with the sample. Carbon nanotubes (CNT) and tobacco mosaic virus (TMV) were the systems studied in this work. Mechanical properties of both the TMV and CNT were performed by means of manipulation experiments. These elongated particles were either pushed across the surface or bent in place by the AFM tip. The bending and buckling responses to the manipulation were analyzed. Among other results, I found the mechanical response of the TMV to be consistent with it having a Young's modulus of {dollar}sim{dollar}1 GPa, and the CNT to be capable of 16% strain with little damage. Studies of friction were also performed on the CNT through manipulation experiments. Stick-slip behavior was observed, the relation between tube diameter and frictional force was explored, and rolling behavior was observed and analyzed. These direct observations of nanometer scale objects rolling on a substrate, are unprecedented to the best of my knowledge.