2015 Senior Design Expo

Six APAM students participated in the 2015 Fu Foundation School of Engineering and Applied Science Senior Design Expo on Thursday, May 7, from 12:00 to 3:00 PM in Roone Arledge Auditorium.

Synthesis of PbS Quantum Dots and Their Size-Dependent Optical Properties
Robyn Ridley
Advisor: Irving Herman

The size-dependent properties of semiconductor nanoparticles, also called quantum dots, offer a wide variety of potential applications in devices such as solar cells, lasers, and sensors. To fully investigate these properties and utilize semiconductor nanoparticles in such applications, it is necessary to have highly repeatable synthesis methods resulting in monodisperse samples of quantum dots. This project demonstrates repeatable methods to synthesize highly monodisperse samples of PbS nanoparticles involving the thermal decomposition of an organometallic lead precursor, incitation of a rapid nucleation event by injection of a sulfur precursor, and growth controlling surfactants at high temperatures. Optical properties, such as the absorption and photoluminescence, of the synthesized PbS nanoparticles are measured using FTIR and spectrometry. Nanoparticle size is determined by the use of transmission electron microscopy (TEM). An analysis of the relationship between PbS quantum dot optical properties and size is carried out using the measurements obtained from these methods.

Laser Crystallization of Zinc oxide Thin Films
Joseph W. Eun
Advisor: James Im

The primary purpose of this project was to determine and understand the effects of laser crystallization and temperature on Zinc oxide thin films, and to find regions at which the thin film underwent a phase transition and minimize cracking and ablation. My investigation involves a series of experiments (at various energy densities and temperatures) and observations using various modes of optical microscopy, scanning electron microscopy, etc.

Benchmarking of Dectris Mythen 1K Strip Detector for Pair Distribution Function Analysis of Synchrotron Diffraction Data
Karim Tanju Mukaddem
Advisor: Simon Billinge

The Mythen 1K Strip Detector from Dectris is an x-ray detector that promises, among many other features, an excellent signal to noise ratio. The purpose of this project is to determine the suitability of the Mythen 1K for atomic pair distribution function (PDF) analysis of synchrotron powder diffraction data and to identify the challenges and advantages that come with it. The project entailed the collection and processing of data from samples with known structures using this detector and benchmarking the obtained PDFs.

Understanding Load Transfer in Steel Suspension Bridge Cables though Pullout Testing and Neutron Diffraction
Srishti Goel
Advisor: Ismail C. Noyan

Suspension bridges are a vital part of the world's transportation infrastructure. Many of them, located in heavily populated areas (such as New York City), are also irreplaceable due to economic constraints. Therefore, it is critically important to have an understanding of load transfer in the cables of the bridge to best optimize maintenance and repair practices. While these practices currently have a solid theoretical basis, there is very little actual experimental data to support them. In this small portion of a much larger endeavor, I conducted a series of tests to understand the effects of novel geometries on load transfer in standard seven-wire bridge cable specimens. I was also able to be part of a deployment to Oak Ridge National Laboratory, SNS, during which the team conducted experiments using neutron diffraction to determine the effect of wire twist on load transfer in a standard seven-wire specimen as well as mapped the effect of clamping on wire interactions in a nineteen-wire sample.

Maximization of Third Harmonic Generation in Few Layer Graphene
Christopher Florencio-Aleman
Advisor: Richard Osgood

Graphene has been a subject of immense interest as of lately but most research is dedicated to studying its electronic and mechanical properties. Graphene also displays promising optical properties suitable for photonic applications. This project seeks to explore the nonlinear optical properties of graphene and the ways in which it can increase the energy of light that it interacts with as a result of increasing the number of graphene layers present in the medium. As the medium increases in layers of graphene, its properties change such that they are desirable for certain photonic applications. The variation in layers changes the electronic structure of the material, which is the main determinant of its optical response. This project sought to find the number of layers at which graphene maximizes its nonlinear optical response as well as creating a model that describes that point.

Laser Induced Phase Transformation of ZnO substrate and SiO2 buffer on a Silicon Wafer
Laticia Lee
Advisor: James Im

The ultimate goal of this project is to figure out properties of ZnO substrate and SiO2 buffer on silicon wafer and use those results to build better smartphone screens and for a variety of other applications.

VIDEO: Senior Design Expo 2015

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