Magister Philosophiae - MPhil (Physics)http://hdl.handle.net/11394/33222024-03-28T17:38:34Z2024-03-28T17:38:34ZSynthesis of bimetallic immiscible alloy nanoparticles through green and gamma radiolysis approaches for environmental remediation applicationsNoukelag, Sandrine Kamdoumhttp://hdl.handle.net/11394/100312023-05-19T00:02:29Z2022-01-01T00:00:00ZSynthesis of bimetallic immiscible alloy nanoparticles through green and gamma radiolysis approaches for environmental remediation applications
Noukelag, Sandrine Kamdoum
The synthesis of bimetallic immiscible alloy nanoparticles (NPs) using versatile routes, is a major concern since physio-chemical methods are not environmentally benign. Breaking down the immiscibility would generate NPs with remarkable properties and consequently more applications. As a result, it urges the development of one-step, eco-friendly, efficient, and reliable methods for getting more metastable bimetallic alloys from immiscible metals. To that aim, unconventional approaches such as green and gamma radiolysis were considered as the paths forward in this thesis. The wide immiscibility gaps of iron-silver (Fe-Ag), and iron-zinc (Fe-Zn) led to their selection
Philosophiae Doctor - PhD
2022-01-01T00:00:00ZTowards stimuli-responsive functional nanocomposites: Smart tunable plasmonic nanostructures au-v02Kama Kama, Jean Boscohttp://hdl.handle.net/11394/88072022-03-08T00:00:22Z2010-01-01T00:00:00ZTowards stimuli-responsive functional nanocomposites: Smart tunable plasmonic nanostructures au-v02
Kama Kama, Jean Bosco
The fascinating optical properties of metallic nanostructures, dominated by collective
oscillations of free electrons known as plasmons, open new opportunities for the
development of devices fabrication based on noble metal nanoparticle composite
materials. This thesis demonstrates a low-cost and versatile technique to produce
stimuli-responsive ultrafast plasmonic nanostructures with reversible tunable optical
properties. Albeit challenging, further control using thermal external stimuli to tune the
local environment of gold nanoparticles embedded in V02 host matrix would be ideal
for the design of responsive functional nanocomposites. We prepared Au-V02
nanocomposite thin films by the inverted cylindrical reactive magnetron sputtering
(ICMS) known as hollow cathode magnetron sputtering for the first time and report the
reversible tuning of surface plasmon resonance of Au nanoparticles by only adjusting
the external temperature stimuli. The structural, morphological, interfacial analysis and
optical properties of the optimized nanostructures have been studied. ICMS has been
attracting much attention for its enclosed geometry and its ability to deposit on large
area, uniform coating of smart nanocomposites at high deposition rate. Before
achieving the aforementioned goals, a systematic study and optimization process of
V02 host matrix has been done by studying the influence of deposition parameters on
the structural, morphological and optical switching properties of V02 thin films. A
reversible thermal tunability of the optical/dielectric constants of V02 thin films by
spectroscopic ellipsometry has been intensively also studied in order to bring more
insights about the shift of the plasmon of gold nanoparticles imbedded in V02 host
matrix.
Magister Philosophiae - MPhil
2010-01-01T00:00:00ZSelection and optimization of the seeding procedure prior to the synthesis of Pd-based membranesMc Donald, Earlhttp://hdl.handle.net/11394/41022018-09-05T10:45:58Z2014-01-01T00:00:00ZSelection and optimization of the seeding procedure prior to the synthesis of Pd-based membranes
Mc Donald, Earl
Pd based membranes are known for their incredible selectivity towards H2. In order for Pd membranes to display high H2 selectivity, a defect free layer of Pd needs to be deposited onto a support. Although various fabrication techniques do exist, many researchers have attempted to produce defect free Pd-based films, using electroless plating. The first step in the preparation technique involves “seeding” of the support structure. Even though these seeds, if well distributed and anchored to the support, are crucial in order to obtain the defect free Pd layer, they hardly ever received attention from the science community. This thesis reports findings on various seeding methods as well as the resulting microstructures of the Pd films formed as a result of the type of seeding method employed. Finally the quality of the membranes using the most promising seeding technique was determined by subjecting the membranes to permeance tests with N2 at both high and low temperatures as well as with H2 at high temperatures.
Magister Philosophiae - MPhil
2014-01-01T00:00:00ZSimulation of silicon and diamond detector systems by GEANT4 simulation techniquesErasmus, Nicholas Rattrayhttp://hdl.handle.net/11394/39142018-07-27T08:32:06Z2014-01-01T00:00:00ZSimulation of silicon and diamond detector systems by GEANT4 simulation techniques
Erasmus, Nicholas Rattray
There is a constant need for improvement in nuclear particle detection methods. Silicon surface barrier detectors have proved very valuable during the last decades. Diamond is a viable alternative to silicon as a semiconductor detector. It offers significant advantages over silicon due to its high radiation hardness and low drift currents.
A Coulomb-excitation study has been carried out at TRIUMF using a 59.7 MeV 12C beam impinging on a 194Pt target. The particles underwent elastic Rutherford scattering in the target, and a double sided silicon S3 CD detector was used to measure the resulting particle energy spectra. These spectra were simulated in GEANT4 and compared to the experimental results. Subsequently, the silicon was replaced with diamond and the simulation was repeated. Such simulations of particle energy spectra, properly incorporating elastic Rutherford scattering, have not been carried out with GEANT4 before. An accurate simulation of the elastic peak obtained from particle spectra will provide a methodology for applying particle-gamma coincidence techniques. The study of the inelastic peak in 12C and similar nuclei will benefit from such developments. Such simulations will also offer high energy calibration points for the experimental data, and the possibility of testing the experimental conditions including the target thickness, beam energy, and linearity of electronic modules (e.g. the preamplifier). The simulation offered results comparable to the experimental case. GEANT4 was found to simulate the Rutherford cross sections at specific scattering angles as well as the position of the simulated energy peaks accurately when compared with the experimental case. As expected, the experimentally obtained particle energy spectra displayed more broadening than the simulated spectra, though the shape of the peaks was very similar. The simulation of the double sided diamond detector was a tentative first step in its testing as a particle detector. The sophisticated methods required to properly simulate and test diamond for nuclear physics experiments were not implemented. This simulation may serve as a starting point for further testing of diamond detectors, using advanced simulation techniques
>Magister Scientiae - MSc
2014-01-01T00:00:00Z