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A Theoretical Investigation of Small Organic Molecules on Transition Metal Surfaces
Title
A Theoretical Investigation of Small Organic Molecules on Transition Metal Surfaces.
Creator
Malone, Walter, Kara, Abdelkader, Stolbov, Sergey, Kaden, William, Thomas, Jayan, University of Central Florida
Abstract / Description
With the ever growing number of proposed desnity functional theory (DFT) functionals it becomes necessary to thoroughly screen any new method to determine its merit. Especially relevant methods include a proper description of the van der Waals (vdW) interaction, which can prove vital to a correct description of a myriad of systems of technological importance. The first part of this dissertation explores the utility of several vdW-inclusive DFT functionals including optB86b-vdW, optB88-vdW,...
Show moreWith the ever growing number of proposed desnity functional theory (DFT) functionals it becomes necessary to thoroughly screen any new method to determine its merit. Especially relevant methods include a proper description of the van der Waals (vdW) interaction, which can prove vital to a correct description of a myriad of systems of technological importance. The first part of this dissertation explores the utility of several vdW-inclusive DFT functionals including optB86b-vdW, optB88-vdW, optPBE-vdW, revPBE-vdW, rPW86-vdW2, and SCAN+rVV10 by applying them to model systems of small organic molecules, pyridine and thiophene, on transition metal surfaces. Overall, we find the optB88-vdW functional gives the best, most balanced description of both thiophene and pyridine on transition metal surfaces while revPBE-vdW, rPW86-vdW2, and SCAN+rVV10 functionals perform especially poorly for these systems. In the second part of this dissertation we change our focus to potential applications of DFT. Specifically, we study the hydrodesulfurization (HDS) process and molecules that could be used in molecular electronics. The removal of sulfur containing molecules from petrochemicals through HDS is an exceptionally important process economically, and the field of molecular electronics is rapidly developing with hopes of competing with and replacing their silicon analogues. First we investigate the hydrodesulfurization of thiophene. In this dissertation we manage to map the HDS rate of thiophene in realistic reaction conditions to the charge transfer and adsorption energy of thiophene on bare transition metal surfaces in hopes of predicting ever more active HDS catalysis. Finally we look at the adsorption of polythiophenes and 5,14-dihydro-5,7,12,14-tetraazapentacene (DHTAP) on Au(111) and Cu(110). We find that polythiophenes may dissociate of Au(111), presenting an issue for their use in molecular electronics. DHTAP, in contrast, proves to a suitable candidate for use practical devices.
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Date Issued
2019
Identifier
CFE0007494, ucf:52653
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007494
Chemistry and dissipation at mineral surfaces in the space environment
Title
Chemistry and dissipation at mineral surfaces in the space environment.
Creator
Tucker, William, Schelling, Patrick, Britt, Daniel, Kara, Abdelkader, Coffey, Kevin, University of Central Florida
Abstract / Description
The composition and morphology of mineral surfaces is known to play an important role in various phenomena relevant to planetary science. For example, the synthesis and processing of complex organics likely occurs at mineral surfaces strongly affected by the space environment. Furthermore, the dissipative and adhesive properties of dust grains may depend strongly on the chemical state of the surface including the presence of dangling bonds, adsorbates, and radicals. In this dissertation,...
Show moreThe composition and morphology of mineral surfaces is known to play an important role in various phenomena relevant to planetary science. For example, the synthesis and processing of complex organics likely occurs at mineral surfaces strongly affected by the space environment. Furthermore, the dissipative and adhesive properties of dust grains may depend strongly on the chemical state of the surface including the presence of dangling bonds, adsorbates, and radicals. In this dissertation, experimental results are first presented which demonstrate that mineral grains subjected to high temperatures in a reducing environment lead to iron nanoparticles which are strongly catalytic for the formation of complex organic species. Next, results obtained using molecular-dynamics simulations demonstrate that uncoordinated surface atoms in metallic nanoparticles result in plastic deformation, strong dissipation and adhesion during collisions. This can be contrasted with previous simulations which demonstrate significantly weaker dissipation when surface atoms are passivated. Calculations of critical sticking velocities demonstrate that simple coarse- grain models are insufficient for predicting the adhesive behavior of sub-micron sized grains. Next, results are presented describing a computational study illuminating the role of surface chemistry on adhesion and dissipation for iron nanoparticle collisions, which in the case of free radical adsorbates may also contribute to the creation of more complex species. Lastly, to further elucidate dissipation, the direct coupling of harmonic vibrational modes in the dissipation process is established. The results demonstrate broad participation of low and high-frequency modes during a collision during a timescale less than time required for particles to rebound. Hence, our results demonstrate extremely strong likelihood of adhesion during collisions. This approach provides a way to use density-functional theory calculations to directly compute dissipative couplings at mineral interfaces.
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Date Issued
2019
Identifier
CFE0007545, ucf:52592
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007545
A theoretical and experimental investigation of the physical and chemical properties of solid nanoscale interfaces
Title
A theoretical and experimental investigation of the physical and chemical properties of solid nanoscale interfaces.
Creator
Matos, Jeronimo, Kara, Abdelkader, Heinrich, Helge, Schelling, Patrick, Masunov, Artem, University of Central Florida
Abstract / Description
With the emerging interest in nanoscale materials, the fascinating field of surface science is rapidly growing and presenting challenges to the design of both experimental and theoretical studies. The primary aim of this dissertation is to shed some light on the physical and chemical properties of selected nanoscale materials at the interface. Furthermore, we will discuss the effective application of cutting edge theoretical and experimental techniques that are invaluable tools for...
Show moreWith the emerging interest in nanoscale materials, the fascinating field of surface science is rapidly growing and presenting challenges to the design of both experimental and theoretical studies. The primary aim of this dissertation is to shed some light on the physical and chemical properties of selected nanoscale materials at the interface. Furthermore, we will discuss the effective application of cutting edge theoretical and experimental techniques that are invaluable tools for understanding the systems at hand. To this effect, we use density functional theory (DFT) with the inclusion of van der Waals (vdW) interactions to study the effect of long-range interactions on the adsorption characteristics of various organic molecules (i.e. benzene, olympicene radical, and sexithiophene) on transition metal surfaces. Secondly, the detailed analysis of x-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements will be presented. These investigations will be dedicated to the study of (i) the effect of pre-treatment on the coarsening behavior of Pt nanoparticles (NPs) supported on ?-Al2O3 and (ii) deconvoluting the intrinsic (size effects) and extrinsic (ligand effects) physical and electronic properties of Au NPs encapsulated by polystyrene 2-vinylpiridine ligands.
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Date Issued
2015
Identifier
CFE0005975, ucf:50783
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005975
Theoretical And Computational Studies Of Diffusion Of Adatom Islands And Reactions Of Molecules On Surfaces
Title
Theoretical And Computational Studies Of Diffusion Of Adatom Islands And Reactions Of Molecules On Surfaces.
Creator
Shah, Syed Islamuddin, Rahman, Talat, Kara, Abdelkader, Schelling, Patrick, Coffey, Kevin, University of Central Florida
Abstract / Description
The work presented in this dissertation focuses on the study of post deposition spatial and temporal evolution of adatom islands and molecules on surfaces using ab initio and semiemperical methods. It is a microscopic study of the phenomena of diffusion and reaction on nanostructured surfaces for which we have developed appropriate computational tools,as well as implemented others that are available. To map out the potential energy surface on which the adatom islands and molecules move, we...
Show moreThe work presented in this dissertation focuses on the study of post deposition spatial and temporal evolution of adatom islands and molecules on surfaces using ab initio and semiemperical methods. It is a microscopic study of the phenomena of diffusion and reaction on nanostructured surfaces for which we have developed appropriate computational tools,as well as implemented others that are available. To map out the potential energy surface on which the adatom islands and molecules move, we have carried out ab initio electronic structure calculations based on density functional theory (DFT) for selected systems. For others, we have relied on semiempirical interatomic potentials derived from the embedded atom method. To calculate the activation energy barriers, we have employed the (")drag(") method in most cases and verified its reliability by employing the more accurate nudged elastic band method for selected systems. Temporal and spatial evolution of the systems of interest have been calculated using the kinetic Monte Carlo (KMC), or the more accurate (complete) Self Learning kinetic Monte Carlo (SLKMC) method in the majority of cases, and ab initio molecular dynamics simulations in others. We have significantly enhanced the range of applicability of the SLKMC method by introducing a new pattern recognitionscheme which by allowing occupancy of the (")fcc(") and (")hcp(") sites (and inclusion of (")top(") site in the pattern recognition as well) is capable of simulating the morphological evolution of three dimensional adatom islands, a feature not feasible via the earlier - proposed SLKMC method. Using SLKMC (which allows only fcc site occupancy on fcc(111) surface), our results of the coarsening of Ag islands on the Ag(111) surface show that during early stages, coarsening proceeds as a sequence of selected island sizes, creating peaks and valleys in the island-size distribution. This island size selectivity is independent of initial conditions andresults from the formation of kinetically stable islands for certain sizes as dictated by the relative energetics of edge atom detachment/attachment processes together with the large activation barrier for kink detachment.On applying the new method, SLKMC-II, to examine the self diffusion of smalladatom islands (1-10 atoms) of Cu on Cu(111), Ag on Ag(111) and Ni on Ni(111), wefind that for the case of Cu and Ni islands, diffusion is dominated by concerted processes(motion of island as a whole), whereas in the case of Ag, islands of size 2-9 atoms diffusethrough concerted motion whereas the 10-atom island diffuses through single atom processes.Effective energy barriers for the self diffusion of these small Cu islands is 0.045 eV/atom,for Ni it is 0.060 eV/atom and for Ag it is 0.049 eV/atom, increasing almost linearly withisland size.Application of DFT based techniques have allowed us to address a few issues stemmingfrom experimental observations on the effect of adsorbates such as CO on the structure and stability of bimetallic systems (nanoparticles and surfaces). Total energy calculationsof Ni-Au nanoparticles show Ni atoms to prefer to be in the interior of the nanoparticle.CO molecules, however, prefer to bind to a Ni atom if present on the surface. Using abinitio molecular dynamics simulations, we confirm that the presence of CO molecule induces diffusion of Ni atom from the core of the Ni-Au nanoparticle to its surface, making the nanoparticle more reactive. These results which help explain a set of experimental data are rationalized through charge transfer analysis.Similar to the case of Ni-Au system, it is found that methoxy (CH$_{3}$O) may also induce diffusion of inner atoms to the surface on bimetallic Au-Pt systems. Our total energy DFT calculations show that it is more favorable for methoxy to bind to a Pt atom in the top Au layer than to a Au atom in Au-Pt system thereby explaining experimental observations.To understand questions related to the dependence of product selectivity on ambientpressure for ammonia decomposition on RuO2(110), we have carried out an extensivecalculation of the reaction pathways and energy barriers for a large number of intermediate products. On combining the reaction energetics from DFT, with KMC simulations, we showthat under UHV conditions, selectivity switches from N2 ( ? 100 % selectivity) at T = 373Kto NO at T = 630K, whereas under ambient conditions, N2 is still the dominant productbut maximum selectivity is only 60%. An analysis based on thermodynamics alone shows a contradiction between experimental data at UHV with those under ambient pressure. Ourcalculations of the reaction rates which are essential for KMC simulations removes this apparentinconsistency and stresses the need to incorporate kinetics of processes in order toextract information on reaction selectivity.
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Date Issued
2013
Identifier
CFE0005254, ucf:50584
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005254
Tuning chemical and optical properties of nanomaterials: From extended surfaces to finite nanoclusters
Title
Tuning chemical and optical properties of nanomaterials: From extended surfaces to finite nanoclusters.
Creator
Hooshmand Gharehbagh, Zahra, Rahman, Talat, Kara, Abdelkader, Kaden, William, Uribe Romo, Fernando, University of Central Florida
Abstract / Description
Modifying the electronic and optical properties of surfaces and nanostructures are in the forefront of surface science. This dissertation's focus is on this problem. The first part is on the adsorption of functionalized naphthalene molecules on Cu(111) surface. The results show that changing the functional group results in modification of charge redistribution at the interface of molecule and surface and the electronic structure of Cu changes. The second part discusses the new Moir(&)#233;...
Show moreModifying the electronic and optical properties of surfaces and nanostructures are in the forefront of surface science. This dissertation's focus is on this problem. The first part is on the adsorption of functionalized naphthalene molecules on Cu(111) surface. The results show that changing the functional group results in modification of charge redistribution at the interface of molecule and surface and the electronic structure of Cu changes. The second part discusses the new Moir(&)#233; structure of h-BN on Rh(111) induced by intrinsic carbon impurities of Rh single crystals. We found that these impurities intercalate between h-BN and Rh(111) with new local properties such as charge transfer from Rh and C atoms to h-BN such as appearance of new states in the BN. The third part is about the study of CO super lattice structure at 1/2ML when adsorbed on Pd(111). By considering all the possible overlayer structures and using several different functionals, we found that two structures can be made by CO adsorbents and all the other structures convert to one of these two. The fourth part is on the electronic and optical properties of ligated Ag44 nanoclusters. Using DFT and TDDFT calculations we show that when the pH level of a solvent is changed, the protecting ligands deprotonate and their interaction with each other as well as the metal core varies and the new peaks in absorption spectrum arise from electron rich deprotonated ligands. The final part is on the adsorption of planar molecules on MoS2. We found that the isomers of di-iodobenzene adsorb with same strength on MoS2 and it is the symmetry of frontier orbitals that identifies their different behavior. Also the adsorption and dissociation of benzenethiol on MoS2 was studied and the results show that benzenethiol dissociates only in the presence of defects and heals the structure.
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Date Issued
2018
Identifier
CFE0007337, ucf:52138
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007337
Multiscale simulation of laser ablation and processing of semiconductor materials
Title
Multiscale simulation of laser ablation and processing of semiconductor materials.
Creator
Shokeen, Lalit, Schelling, Patrick, Kar, Aravinda, Vaidyanathan, Rajan, Su, Ming, Kara, Abdelkader, University of Central Florida
Abstract / Description
We present a multiscale model of laser-solid interactions in silicon based on an empirical potential developed under conditions of strong electronic excitations. The parameters of the interatomic potential depends on the temperature of the electronic subsystem Te, which is directly related to the density of the electron-hole pairs and hence the number of broken bonds. We analyze the dynamics of this potential as a function of electronic temperature Te and lattice temperature Tion. The...
Show moreWe present a multiscale model of laser-solid interactions in silicon based on an empirical potential developed under conditions of strong electronic excitations. The parameters of the interatomic potential depends on the temperature of the electronic subsystem Te, which is directly related to the density of the electron-hole pairs and hence the number of broken bonds. We analyze the dynamics of this potential as a function of electronic temperature Te and lattice temperature Tion. The potential predicts phonon spectra in good agreement with finite-temperature density-functional theory (DFT), including the lattice instability induced by the high electronic excitations. For 25fs pulse, a wide range of fluence values is simulated resulting in heterogeneous melting, homogenous melting, and ablation. The results presented demonstrate that phase transitions can usually be described by ordinary thermal processes even when the electronic temperature Te is much greater than the lattice temperature TL during the transition. However, the evolution of the system and details of the phase transitions depend strongly on Te and corresponding density of broken bonds. For high enough laser fluence, homogeneous melting is followed by rapid expansion of the superheated liquid and ablation. Rapid expansion of the superheated liquid occurs partly due to the high pressures generated by a high density of broken bonds. As a result, the system is readily driven into the liquid-vapor coexistence region, which initiates phase explosion. The results strongly indicates that phase explosion, generally thought of as an ordinary thermal process, can occur even under strong non-equilibrium conditions when Te (>)(>)TL. In summary, a detailed investigation of laser-solid interactions in silicon is presented for femtosecond laser pulse that yields strong far-from-equilibrium conditions.
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Date Issued
2012
Identifier
CFE0004599, ucf:49206
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004599
Size, Shape, Composition and Chemical state effects in nanocatalysis
Title
Size, Shape, Composition and Chemical state effects in nanocatalysis.
Creator
Ahmadi, Mahdi, Roldan Cuenya, Beatriz, Rahman, Talat, Kara, Abdelkader, Coffey, Kevin, University of Central Florida
Abstract / Description
The field of nanocatalysis has gained significant attention in the last decades due to the numerous industrial applications of nanosized catalysts. Size, shape, structure, and composition of the nanoparticles (NPs) are the parameters that can affect the reactivity, selectivity and stability of nanocatalysts. Therefore, understanding how these parameters affect the catalytic properties of these systems is required in order to engineer them with a given desired performance. It is also important...
Show moreThe field of nanocatalysis has gained significant attention in the last decades due to the numerous industrial applications of nanosized catalysts. Size, shape, structure, and composition of the nanoparticles (NPs) are the parameters that can affect the reactivity, selectivity and stability of nanocatalysts. Therefore, understanding how these parameters affect the catalytic properties of these systems is required in order to engineer them with a given desired performance. It is also important to gain insight into the structural evolution of the NP catalysts under different reaction conditions to design catalysts with long durability under reaction condition. In this dissertation a synergistic combination of in situ, ex situ and operando state-of-the art techniques have allowed me to explore a variety of parameters and phenomena relevant to nanocatalysts by systematically tuning the NP size, chemical state, composition and chemical environment.
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Date Issued
2016
Identifier
CFE0006243, ucf:51084
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006243
Density-Functional Theory+Dynamical Mean-Field Theory Study of the Magnetic Properties of Transition-Metal Nanostructures
Title
Density-Functional Theory+Dynamical Mean-Field Theory Study of the Magnetic Properties of Transition-Metal Nanostructures.
Creator
Kabir, Alamgir, Rahman, Talat, Kara, Abdelkader, Del Barco, Enrique, Kik, Pieter, University of Central Florida
Abstract / Description
In this thesis, Density Functional Theory (DFT) and Dynamical Mean-Field Theory (DMFT) approaches are applied to study the magnetic properties of transition metal nanosystems of different sizes and compositions. In particular, in order to take into account dynamical electron correlation effects (time-resolved local charge interactions), we have adopted the DFT+DMFT formalism and made it suitable for application to nanostructures. Preliminary application of this DFT+DMFT approach, using...
Show moreIn this thesis, Density Functional Theory (DFT) and Dynamical Mean-Field Theory (DMFT) approaches are applied to study the magnetic properties of transition metal nanosystems of different sizes and compositions. In particular, in order to take into account dynamical electron correlation effects (time-resolved local charge interactions), we have adopted the DFT+DMFT formalism and made it suitable for application to nanostructures. Preliminary application of this DFT+DMFT approach, using available codes, to study the magnetic properties of small (2 to 5-atom) Fe and FePt clusters provide meaningful results: dynamical effects lead to a reduction of the cluster magnetic moment as compared to that obtained from DFT or DFT+U (U being the Coulomb repulsion parameter). We have subsequently developed our own nanoDFT+DMFT code and applied it to examine the magnetization of iron particles containing10-147 atoms. Our results for the cluster magnetic moments are in a good agreement with experimental data. In particular, we are able to reproduce the oscillations in magnetic moment with size as observed in the experiments. Also, DFT+DMFT does not lead to an overestimation of magnetization for the clusters in the size range of 10-27 atoms found with DFT and DFT+U. On application of the nanoDFT+DMFT approach to systems with mixed geometry (-) Fe2O3 film, which are periodic (infinitely extended), in two directions, and finite in the third. Similar to DFT+U, we find that the surface atom magnetic moments are smaller compared to the bulk. However, the absolute values of the surface atoms magnetic moments are smaller in DFT+DMFT. In parallel, we have carried out a systematic study of magnetic anisotropy in bimetallic L10 FePt nanoparticles (20-484 atoms) by using two DFT-based approaches: direct and the torque method. We find that the magnetocrystalline anisotropy (MCA) of FePt clusters is larger than that of the pure Fe and Pt ones. We explain this effect by a large hybridization of 3d Fe- and 5d Pt-atom orbitals, which lead to enhancement of the magnetic moment of the Pt atom, and hence to a larger magnetic anisotropy because of large spin-orbit coupling of Pt atoms. In addition, we find that particles whose (large) central layer consists of Pt atoms, rather than Fe, have larger MCA due to stronger hybridization effects. Such 'protected' MCA, which does not require protective cladding, can be used in modern magnetic technologies.
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Date Issued
2015
Identifier
CFE0006038, ucf:50971
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006038
Atomic-scale simulation of physical and chemical processes during space weathering and planet formation
Title
Atomic-scale simulation of physical and chemical processes during space weathering and planet formation.
Creator
Quadery, Abrar, Schelling, Patrick, Britt, Daniel, Peale, Robert, Kara, Abdelkader, Sohn, Yongho, University of Central Florida
Abstract / Description
We investigate the mechanisms of space weathering and dust grain collisions, two topics of interests from planetary sciences, using atomic-scale simulations. Space weathering is the change in chemical and physical properties of minerals exposed to solar radiation and micrometeorite bombardment on surfaces of airless planetary bodies like the Moon and asteroids. An understanding of the connection between the surface evolution of the minerals and the underlying thermodynamic and kinetic factors...
Show moreWe investigate the mechanisms of space weathering and dust grain collisions, two topics of interests from planetary sciences, using atomic-scale simulations. Space weathering is the change in chemical and physical properties of minerals exposed to solar radiation and micrometeorite bombardment on surfaces of airless planetary bodies like the Moon and asteroids. An understanding of the connection between the surface evolution of the minerals and the underlying thermodynamic and kinetic factors is still missing. We address this issue and determine the time evolution of Frenkel defects in the silicate minerals olivine ((Mg,Fe)$_2$SiO$_4$) and orthopyroxene ((Mg,Fe)SiO$_3$) using molecular dynamics with a pair potential. Defect diffusion and clustering are observed in both the minerals. Cation diffusion occurs more readily in olivine than in orthopyroxene and leads to faster annealing in the former. In orthopyroxene, diffusion of anion defects, especially oxygen interstitials, occurs more rapidly and also exhibits anisotropy, which hinders the annealing process. This difference in defect evolution may explain the experimental observation that surface modifications due to irradiation is more pronounced in orthopyroxene than in olivine. Dust grain collision is the dominant process in the initial stage of planet formation, however, the mechanisms by which dust grains grow to larger aggregates and eventually to kilometer sized planetesimal is still not understood. We explore the role of surface chemistry in energy dissipation and grain adhesion during collision of amorphous silica (SiO$_2$) nanograins using molecular dynamics with a reactive potential, namely ReaxFF. We found nonhydroxylated amorphous silica nanoparticles stick with higher probability than their hydroxylated counterpart. This difference is attributed to the preponderance of unsatisfied dangling bonds on the dry silicate surface which facilitate bond formation during collision, and thereby provide a mechanism for energy dissipation. The speed below which sticking occurs in the dry nanograins is much higher than that found in Earth-based experiments, which suggests any experimental study of dust grain collision should take into account of the chemical environment. We probe into the nanograin collisions further and carry out atomistic simulatons of collisions of molten silica nanograins. We observed in the molten state, amorphous silica is more sticky than it is in the solid phase. This happens due to increased viscoelastic energy dissipation. The result may explain how rocky planets originated from the inner rings of the protoplanetay disks where temperatures were as high as $\sim$ 2000 K. In order to increase the range of materials that could be simulated with ReaxFF potential, and also to examine the different oxidation states of iron associated with nanophase iron formation during space weathering, we made attempt to develop ReaxFF potential for fayalite (Fe$_2$SiO$_4$). We found out fundamental limitations of ReaxFF model to describe three-component minerals. However, during the fitting process we developed a model for iron silicide (FeSi), and made attempt to improve the silica model to obtain better elastic properties. We report here the fitting processes and the observed limitations of ReaxFF model.
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Date Issued
2017
Identifier
CFE0006907, ucf:51691
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006907
Structure, stability, vibrational, thermodynamic, and catalytic properties of metal nanostructures: size, shape, support, and adsorbate effects
Title
Structure, stability, vibrational, thermodynamic, and catalytic properties of metal nanostructures: size, shape, support, and adsorbate effects.
Creator
Behafarid, Farzad, Roldan Cuenya, Beatriz, Chow, Lee, Heinrich, Helge, Kara, Abdelkader, Schoenfeld, Winston, University of Central Florida
Abstract / Description
Recent advances in nanoscience and nanotechnology have provided the scientific community with exciting new opportunities to rationally design and fabricate materials at the nanometer scale with drastically different properties as compared to their bulk counterparts. In this dissertation, several challenges have been tackled in aspects related to nanoparticle (NP) synthesis and characterization, allowing us to make homogenous, size- and shape-selected NPs via the use of colloidal chemistry,...
Show moreRecent advances in nanoscience and nanotechnology have provided the scientific community with exciting new opportunities to rationally design and fabricate materials at the nanometer scale with drastically different properties as compared to their bulk counterparts. In this dissertation, several challenges have been tackled in aspects related to nanoparticle (NP) synthesis and characterization, allowing us to make homogenous, size- and shape-selected NPs via the use of colloidal chemistry, and to gain in depth understanding of their distinct physical and chemical properties via the synergistic use of a variety of ex situ, in situ, and operando experimental tools. A variety of phenomena relevant to nanosized materials were investigated, including the role of the NP size and shape in the thermodynamic and electronic properties of NPs, their thermal stability, NP-support interactions, coarsening phenomena, and the evolution of the NP structure and chemical state under different environments and reaction conditions.
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Date Issued
2012
Identifier
CFE0004779, ucf:49796
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004779