Nanomechanical cutting of carbon nanotubes and folding of graphene on flat substrate.

摘要

High-precision length control of carbon nanotube (CNTs) is of importance to the operation and performance of nanotube-based systems and devices. In this thesis, an experimental study of cutting individual CNTs using atomic force microscopy (AFM) techniques is presented. In the nanotube cutting experiment, a CNT standing still on a flat silicon substrate is laterally scribed by an AFM tip. The tube is fractured by the tip-tube collision force at the collision site through increasing the applied normal force. Based on the measured cutting forces, the fracture (breaking) strengths of the tested CNTs are calculated to be in the range of 5.5--70 GPa using contact mechanics theories. This thesis also presents a nanomechanical study of graphene folding on flat substrates. The structure and deformation of self-folded graphene sheets are characterized by using AFM. The results indicate that the hump height of 2--6 layers graphene follows a nearly linear relationship with its thickness. The work presented in this thesis contributes to a better understanding of the structural and mechanical properties of CNTs and graphene, and is useful in the pursuit of their applications.