Theoretical Modelling and Characterisation of Concerted Tip and Surface Effects in NC-AFM
type: CreativeWork
description: Rising interest in functionalising molecules and surface and building nano-devices, that is nanotechnology, has in uenced demand for techniques that image molecules and surfaces with atomic precision. One such technique that has answered this call is Non-Contact Atomic Force Microscopy (NC-AFM), which has a very successful history of directly probing many atomic properties on a wide variety of systems. Interpretation of measurements, however, is highly dependent on knowledge of the atomic probe tip, which is generally elusive and is the most problematic issue surrounding the eld. Another such issue is in understanding the atomic processes behind measurements, which to a large extent, also depends on knowledge of the atomic tip termination. Since its development, theorists have been attempting to ll in this knowledge gap, making signicant progress, but a substantial gap still remains. This thesis therefore addresses these two issues from a theoretical viewpoint. After describing the theoretical model used to simulate NC-AFM behaviour, it is used in conjunction with various theoretical techniques to study three important eects on NC-AFM measurements contributing to these issues: dierent tip terminations, chemical and structural; the relative stabilities of the surfaces and instabilities within the surface; surfaces defects. The systems studied were the p(2 1) and c( 6 1) reconstructions of the oxidised copper (110) surface and the buckled dimer c(4 2) reconstruction of the silicon (001) surface. The stabilities of the two Cu(110):O surfaces were studied thermodynamically, where conventional theoretical methods were found to unexpectedly fail to accurately describe them, and corrections for this were studied. Using this knowledge, NC-AFM simulations were performed using two dierent chemical tip terminations, and were compared to experimental results, where tip identication was found to be possible on the c( 6 1) surface and the p(2 1) surface if a common ad-atom defect…
abstract: Rising interest in functionalising molecules and surface and building nano-devices, that is nanotechnology, has in uenced demand for techniques that image molecules and surfaces with atomic precision. One such technique that has answered this call is Non-Contact Atomic Force Microscopy (NC-AFM), which has a very successful history of directly probing many atomic properties on a wide variety of systems. Interpretation of measurements, however, is highly dependent on knowledge of the atomic probe tip, which is generally elusive and is the most problematic issue surrounding the eld. Another such issue is in understanding the atomic processes behind measurements, which to a large extent, also depends on knowledge of the atomic tip termination. Since its development, theorists have been attempting to ll in this knowledge gap, making signicant progress, but a substantial gap still remains. This thesis therefore addresses these two issues from a theoretical viewpoint. After describing the theoretical model used to simulate NC-AFM behaviour, it is used in conjunction with various theoretical techniques to study three important eects on NC-AFM measurements contributing to these issues: dierent tip terminations, chemical and structural; the relative stabilities of the surfaces and instabilities within the surface; surfaces defects. The systems studied were the p(2 1) and c( 6 1) reconstructions of the oxidised copper (110) surface and the buckled dimer c(4 2) reconstruction of the silicon (001) surface. The stabilities of the two Cu(110):O surfaces were studied thermodynamically, where conventional theoretical methods were found to unexpectedly fail to accurately describe them, and corrections for this were studied. Using this knowledge, NC-AFM simulations were performed using two dierent chemical tip terminations, and were compared to experimental results, where tip identication was found to be possible on the c( 6 1) surface and the p(2 1) surface if a common ad-atom defect…
author: Bamidele, Joseph
language: eng
date published: 2013-6-1
date modified: 2026-07-24T02:44:34Z
provider: King's College London
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: King's College London