Identifier

etd-11182010-192232

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Studies of the surface assembly and molecular organization of organic thin films were studied using scanning probe microscopy (SPM) and scanning probe lithography (SPL). Systems of organic thin films such as n-alkanethiols and pyridyl functionalized porphyrins were characterized at the molecular level, and measurements of the conductive properties of polythiophenes containing in-chain cobaltabisdicarbollides were accomplished. Understanding the self-organization and mechanisms of self-assembly of organic molecules provides fundamental insight for structure/property interrelationships. Investigations of the surface assembly of 5,10-diphenyl-15,20-di-pyridin-4-yl-porphyrin (DPP) on Au(111) were done using SPL methods of nanoshaving and nanografting. Automated computer designs were developed for nanofabrication to provide local characterizations of the thickness of DPP films and nanostructures. Nanolithography was accomplished using DPP films as either matrix self-assembled monolayers (SAMs) or as molecules for nanofabrication. Results presented in this dissertation demonstrate that DPP forms compact layers on Au(111), which can be used for inscribing nanopatterns of n-alkanethiols. Arrays of DPP nanopatterns with precise geometries and alignment were fabricated within n-alkanethiols by nanografting, demonstrating nanoscale lithography with pyridyl porphyrins can be accomplished to produce an upright surface orientation on Au(111) mediated by nitrogen-gold chemisorption. Beyond research investigations, the applicability of atomic force microscopy (AFM) and advancements with automated SPL were applied for teaching undergraduate chemistry laboratories to introduce the fundamentals of surface chemistry and molecular manipulation. New classroom activities were developed for the Chemistry 3493 Physical Chemistry laboratory to give students “hands-on” training with AFM. Undergraduates were trained to prepare nanopatterns of n-alkanethiols using software to control the position, force and speed of the AFM tip for nanolithography experiments. The sensitivity and nanoscale resolution of current sensing AFM was applied for studies of the conductive properties of electropolymerized thin films of polythiophenes with cobaltabisdicarbollide moieties. Images acquired with AFM furnished views of the morphology of different polymers prepared on gold surfaces. Surface maps of the conductivity of electropolymerized films were acquired with AFM current images. These studies provide new insight of the effects of the bound cobaltabisdicarbollide moiety and coordinated metal centers for the electronic properties of the resulting conducting materials.

Date

2010

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Jayne C. Garno

Included in

Chemistry Commons

Share

COinS