Doctor of Philosophy (PhD)
Scanning probe microscopy (SPM) for conducting surface characterizations of nanomaterials and molecular self-assembly processes is emerging as an important contribution in nanotechnology, especially towards the design of molecular electronic devices. Another area of importance is the characterization of the properties of nanomaterials for fundamental understanding of structure-function inter-relationships. Understanding the properties and behavior of molecules and finding approaches to control surface self-organization through nanolithography provides essential information for the development of workable applications for nanotechnology. This dissertation describes the methodologies of AFM for characterizing molecules and nanostructures produced with scanning probe lithography (SPL). Automated software for nanografting and nanoshaving produce local nanopatterned surfaces with properties that can be tailored by selected head group chemistries of self-assembled monolayers (SAMs). Nanografting controls the vertical orientation of n-alkanethiols or á,ù-alkanedithiols to exclusively generate layers with a standing-up configuration. Reactive head groups of SAMs, such as carboxyl and thiol groups, also have a role in surface self-assembly, and changes in experimental parameters of concentration are shown to generate thin films of double layers on Au(111). The second part of this dissertation presents the application of AFM for characterization of the arrangement, morphology, and properties of systems of nanopigments and magnetic metal nanoparticles. For thin films of organic dye dispersions composed of pigment nanoparticles, the stability and spectral properties were examined using AFM as well as other established analytical techniques. Changes in surface aggregation are clearly revealed in the AFM results. The study of magnetic properties of metal nanoparticles is a new direction for AFM investigations, which involves characterizing the magnetic response at the level of single nanoparticle measurements. Mapping the magnetic response of synthesized magnetic iron, nickel, and iron(III)-nickel nanoparticles was accomplished using a hybrid AFM imaging mode termed magnetic sample modulation (MSM). Corresponding changes in size versus the amplitude of vibrational response were clearly detected using MSM mode for nanoparticles as small as 1 nm in diameter. Changes to experimental parameters, such as driving frequency and AC electromagnetic field strength, were systematically investigated with MSM to evaluate the selectivity, sensitivity, and detection thresholds for sample characterizations.
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Kelley, Algernon Tremayne, "Applying scanning probe microscopy for the investigation of molecular self-assembly mechanisms and properties of designed nanomaterials" (2009). LSU Doctoral Dissertations. 1083.
Garno, Jayne C.