The purpose of the research in this dissertation was to elucidate the intrinsic properties of how nanoparticles are different from bulk materials. This was done by mechanical and electronic studies of the properties of designed nanoparticles using advanced modes of atomic force microscopy. Information relating to the work functions, contact potential difference, Youngs Moduli, elasticity, and viscoelasticity can be investigated using state-of-the-art atomic force microscope (AFM) experiments.
Subsurface imaging of polystyrene encapsulated cobalt nanoparticles was achieved for the first time using Force Modulation Microscopy (FMM) in conjunction with contact mode AFM. Previously prepared sample of polystyrene coated cobalt nanoparticles were studied. Tapping-mode AFM was used to evaluate the size of coated nanoparticles. Force modulation microscopy was used to visualize details of the outer polystyrene coating. Differences between the softer polystyrene outer coating and the harder cobalt nanoparticle core was visualized based upon the elastic and viscoelastic properties. Variances in sample elasticity were monitored via the amplitude channel that monitors the oscillation amplitude of the cantilever while scanning. Viscoelastic differences were mapped by the phase channel which provides information of the phase lag of the probe.
The identification of designed nanoparticles based upon electrochemical properties was evaluated using the Kelvin Probe Force Microscopy (KPFM) mode of AFM. The contact potential difference between the tip and the sample is measured using an AC bias that is offset with a compensating DC bias while operating in either tapping-mode or non-contact mode AFM. The contact potential difference is more commonly referred to as the difference in work function between the tip and the sample. The work function of a material can be calculated using a reference material with a known work function. Cobalt nanoparticles and gold nanoparticles were imaged using KPFM and baseline experimental contact potential difference values were obtained. Thus far, co-deposition of a mixed nanoparticle solution led to inconclusive results as the experimental and theoretical contact potential difference values were calculated. However, future studies relating to this experiment are planned.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-01122017-064431 |
| Date | 24 January 2017 |
| Creators | Deese, Steve Matthew |
| Contributors | Haber, Louis, Garno, Jayne, Stanley, George G., Sabliov, Christina |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-01122017-064431/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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