<p> A quantum particle moving in a periodic potential, with periodicity d, when acted by an external constant force F undergoes the dynamical phenomenon of Bloch-Zener oscillations (BZO). We investigate BZO of a neutral cold atom in an optical cavity pumped by a laser. We find that the single mode electromagnetic field of the optical cavity is affected by the atomic dynamics and propose the idea that a measurement of the electromagnetic field leaking out of the cavity will reflect the BZO frequency WB = Fd/h, and can be used for a precision measurement of F. The motivation for such a study comes from the fact that if the force F is gravity, then one can probe gravitational forces on sub-millimeter scales since the size of these systems are generally a few hundreds of microns. Such a study can be used to detect deviations from Newtonian gravity at short range proposed by some theories beyond the standard model of particle physics. </p> / Thesis / Master of Science (MSc)

Controlled decarburization experiments were carried out on ternary and quaternary iron alloys. The planar ferrite interfaces formed during decarburization were subsequently investigated using atom probe tomography (APT) to measure interfacial segregation. The segregation results for the Fe-Si-C, Fe-Mn-C, and Fe-Mo-C were used to improve the three-jump-model developed Zurob et al. These three systems were accurately modelled using interfacial binding energy values in agreement with the atom probe tomography results. Qualitative explanations for the modelling results of Sun et al. on the Fe-Mn-Mo-C system and Qiu et al. on the Fe-Mn-Si-C system have also been provided using the results from the atom probe tomography investigation. / Thesis / Master of Applied Science (MASc) / Controlled decarburization experiments were carried out on ternary and quaternary iron alloys. The planar ferrite interfaces formed during decarburization were subsequently investigated using atom probe tomography (APT) to measure interfacial segregation. The segregation results for the Fe-Si-C, Fe-Mn-C, and Fe-Mo-C were used to improve the three-jump-model developed Zurob et al. These three systems were accurately modelled using interfacial binding energy values in agreement with the atom probe tomography results. Qualitative explanations for the modelling results of Sun et al. on the Fe-Mn-Mo-C system and Qiu et al. on the Fe-Mn-Si-C system have also been provided using the results from the atom probe tomography investigation.

Single atom catalysis is a relatively new form of heterogeneous catalysis. While single atom catalysts probably are already used in a lot of catalysis, their identification and characterization has only recently become common place. As we now have the ability to synthesis relatively pure systems consisting of single atoms and then to characterize them, there are many interesting questions that we can answer about them. In this work we will use a combination of several different types of characterizations such as kinetic measurements, diffuse reflectance infrared Fourier transform spectroscopy, extended x-ray absorption fine structure, and many more to better understand how single atoms react and how we can attempt to make such systems more active. The work here is primarily based around Ir single atoms and/or small clusters on three different supports MgAl2O4, TiO2, and CeO2. In each of these cases we attempt to understand how the Ir and the support catalytically oxidize CO into CO2 through a kinetic, and if possible, mechanistic study. Through these mechanistic studies we attempt to isolate the most important parameters of the catalyst so that we can create a more active catalyst. There are, of course, many different ways that we can use this information. The most obvious is by changing the catalyst support, but as the breadth of the research presented here will show, we can also optimize catalytic activity through using mixtures of single atoms with larger species as well as by changing the nuclearity of the said species, i.e., we can increase activity by controlling the size of the catalysts. However, in order to be able to control the activity in this way, we must 1) know how the size affects the activity and 2) know how the reaction conditions affect the size, i.e., we must establish the catalyst size is stable during reaction. Each of these topics are discussed to some extent here. Additionally, we also discuss how different sites of single atoms on the same support might differ and we show that we can create such different sites. On the whole, we have studied single atom and small cluster catalysis in many different directions based on systems of Ir for CO oxidation. This work is also performed with the intent to compare these Ir systems to similar systems of Rh, Pt, Pd, etc. However here we will only discuss the Ir pieces. / Doctor of Philosophy / In this work we study various properties of Ir single atom and subnanometer cluster catalysts for CO oxidation in hopes that we might be able to design a better catalyst with this information. A catalyst is a substance that facilitates a chemical reaction but is not consumed. For this work we will be considering the reaction of carbon monoxide (CO), which is a common pollutant and highly toxic gas, with O2 to create CO2, a much less dangerous pollutant. Our catalyst thus makes this reaction happen much faster and thus allows us to remove CO from exhaust streams, such as car exhaust, better. A single atom catalyst is a catalyst that is primarily a single atom on a metal oxide support. A subnanometer cluster catalyst is thus a catalyst that is smaller than one nanometer (0.00000004 inches). These are typically 10-20 atoms grouped together. This size is interesting as it is bigger than a single atom, but it is still much smaller than a classical catalyst nanoparticle and is thus controlled or dominated by different properties. In this work we will look at how different characteristics of the singe atom and cluster catalysts affect how good of a catalyst it is. The first is how the amount of single atoms and nanoparticles affect the overall activity of the catalyst. This study will tell us what the best mixture of single atoms is. The second study is how small clusters of Ir/MgAl2O4 react differently than single atoms and large nanoparticles. This tells us what the best size for Ir/MgAl2O4 catalysts are. The third study tells us how Ir/TiO2 single atom catalysts react which is useful when compared to Ir/MgAl2O4 and Ir/CeO2 (Chapter 7). The combination of single atom studies then allows us to make predictions on which supports (apart from Ir/MgAl2O4, Ir/TiO2, and Ir/CeO2) will be the best for CO oxidation. The fourth study compares different single atoms (all of Ir/TiO2) and shows how they behave differently, this is another possibility to increase the effectiveness of the catalyst. The fifth study discusses how different conditions affect the size of the Ir/TiO2 catalysts. Specifically, whether they exist as single atoms, subnanometer clusters, or larger clusters. All of these different studies represent another way that we can potentially increase catalytic activity and hopefully will allow our group, or another group to create even more active catalysts.

Quantum dots, also known as artificial atoms, are created by tightly confining electrons, and thereby quantizing their energies. They are important components in the emerging fields of nanotechnology where their potential uses vary from dyes to quantum computing qubits. Interesting properties to investigate are e.g. the existence of atom-like shell structures and lifetimes of prepared states. Stability and controllability are important properties in finding applications to quantum dots. The ability to prepare a state and change it in a controlled manner without it loosing coherence is very useful, and in some semiconductor quantum dots, lifetimes of up to several milliseconds have been realized. Here we focus on dots in semiconductor materials and investigate how the confined electrons are effected by their experienced potential. The shape of the dot will effect its properties, and is important when considering a suitable model. Structures elongated in one dimension, often called nanowires, or shaped as rings have more one-dimensional characteristics than completely round or square dots. The two-dimensional dots investigated here are usually modeled as harmonic oscillators, however we will also consider circular well models. The effective potential confining the electrons is investigated both in regard to how elliptical it is, as well as how results differ when using a harmonic oscillator or a circular well potential. By mixing spin states through spin-orbit interaction transitioning between singlet and triplet states becomes possible with spin independent processes such as phonon relaxation. We solve the spin-mixing two-electron problem numerically for some confinement, and calculate the phonon transition rate between the lowest energy singlet and triplet states using Fermi's golden rule. The strength of the spin-orbit interaction is varied both by changing the coupling constants, and by applying an external, tilted, magnetic field. The relation between magnetic field parameters and dot parameters are used to maximize state lifetimes, and to model experimental results. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

Ultra-violet and visible light induced processes in small organic molecules play very important roles in many fields, e.g., environmental sciences, biology, material development, chemistry, astrophysics and many others. Thus it is of great importance to better understand the mechanisms behind these processes. To achieve this, a bottom-up approach is most effective, where the photo-induced dynamics occurring in the simplest organic molecule (ethylene) are used as a starting point. Simple substituents and functional groups are added in a controlled manner to ethylene, and changes in the dynamics are investigated as a function of these modifications. In this manner, the dynamics occurring in more complex systems can be explored from a known base. In this thesis, the excited state dynamics of small organic molecules are studied by a combination of time-resolved photoelectron spectroscopy and various computational methods in order to determine the basic rules necessary to help understand and predict the dynamics of photo-induced processes. The dynamics occurring in ethylene involve a double bond torsion on the ππ* excited state, followed by the decay to the ground state coupled with pyramidalization and hydrogen migration. Several different routes of chemical modification are used as the basis to probe these dynamics as the molecular complexity is increased. (i) When ethylene is modified by the addition of an alkoxyl group (-OCnH2n+1), a new bond cleavage reaction is observed on the πσ* state. When modified by a cyano (-CN) group, a significant change in the carbon atom involved in pyramidalization is observed. (ii) When ethylene used to build up small cyclic polyenes, it is observed that the motifs of the ethylene dynamics persist, expressed as ring puckering and ring opening. (iii) In small heteroaromatic systems, i.e., an aromatic ring containing an ethylene-like sub-structure and one or two non-carbon atoms, the type of heteroatom (N: pyrrole, pyrazole O: furan) gives rise to different bond cleavage and ring puckering channels. Furthermore, adding an aldehyde group (-C=O) onto furan, as a way to lengthen the delocalised ring electron system, opens up additional reaction channels via a nπ* state. The results presented here are used to build up a more complete picture of the dynamics that occur in small molecular systems after they are excited by a visible or UV photon, and are used as a basis to motivate further investigations. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript. Paper 6: Manuscript.</p>

Knowledge of the atomic number (Zt) dependence of ion-induced electron emission yields (Y) can be the basis for a general understanding of ion-atom interaction phenomena and, in particular, for the design of Zrsensitive detectors that could be useful, for example, in the separation of isobars in accelerator mass spectrometry. The Zx dependence of ion-induced electron emission yields has been investigated using heavy ions of identical velocity (v = 2 v0, with v0 as the Bohr velocity) incident in a normal direction on sputter-cleaned carbon foils. Yields measured in this work plotted as a function of the ion's atomic number reveal an oscillatory behavior with pronounced maxima and minima. This nonmonotonic dependence of the yield on Zx will be discussed in the light of existing theories.

The main topic of this project is the so called Edelstein effect. This recently discovered effect consists in the possibility of converting an electric field (a current) into a magnetization in materials that fulfill specific characteristics, more specifically materials where an effective Rashba spin-orbit coupling is present. The Edelstein effect is appealing to the scientific community from the fundamental physics point of view as well as from the technological point of view. In fact the possibility of efficiently converting an electric signal into a magnetic signal could revolutionize the current information storage technology. In this project, after a study of basic concepts of solid state physics: crystal structure, Bloch's theorem, spin-orbit coupling; we addressed the study of the basics of a powerful numerical tool, called density functional theory (DFT), for predicting the electronic properties of solids. This tool provides us with all the needed quantities for numerically calculating any kind of linear response, which we show that the Edelstein effect is a specific form of. Using a specific implementation of DFT, called augmented spherical wave (ASW), we calculate the Edelstein effect in iron and copper (where no effect is expected) and manganese silicide (where the effect is expected to appear). We also perform a systematic study on how the Edelstein effect depends on the symmetry of the material and the magnitude of the spin-orbit coupling. The calculations showed promising results from which we concluded that the numerical methods used could clearly distinguish between the presence of the Edelstein effect or not in mentioned materials.

Water is a fundamental part of life as we know it, and by that also a fundamental for biology, chemistry, and parts of physics. Understanding how water behaves and interacts is key in many fields of all these three branches of science. Numerical simulation using molecular dynamics can aid in building insight in the behavior and interactions of water. In this thesis molecular dynamics is used to simulate common rigid 3 point water models to see how well they replicate certain physical and chemical properties as functions of temperature. This is done with molecular dynamics program GROMACS which offers a complete set of tools to run simulations and analyze results. Everything has been automated to work with a python script and a file of input parameters. Most of the models follow the same trends and are valid within a limited temperature range. / Vatten är en av de fundamentala byggstenarna för liv, därmed är det även fundamentalt för biologi, kemi och delar av fysiken. Att förstå hur vatten beter sig och interagerar är en stor fråga inom dessa tre grenar av vetenskap. Med molekyldynamik går det att utföra numeriska simuleringar som kan användas som hjälpmedel för att bygga en djupare förståelse för riktigt vatten. I den här uppsatsen så har molekyldynamik använts till att simulera vanliga rigida 3 punkts parametiseringar av vatten för att se hur bra de kan replikera vissa egenskaper som funktioner av temperatur. Simuleringen är gjord med hjälp av molekyldynamik programet GROMACS som ger en fullständig uppsättning verktyg för att simulera och analysera molekylsystem. Alla simuleringar och analys är automatiserat med ett pythonprogram och en fil för parametrar. De allra flesta modeller följer liknande trender och är giltiga inom små temperaturintervall.

Nas instituições arquivísticas, as imagens estão cada vez mais acessíveis através da web. A pesquisa analisa a descrição dos documentos fotográficos digitais neste contexto, sejam eles produtos da digitalização da imagem física, isto é, produzida em processos analógicos, ou das imagens nato-digitais. Visa analisar o acesso em ambientes virtuais, através da padronização das normas de descrição arquivística. Para isso, foi utilizado o AtoM, software desenvolvido pelo Conselho Internacional de Arquivo (CIA), ferramenta totalmente voltada para web, que segue padrões de normas arquivísticas como a ISAD(G). Com o objetivo de complementar as especificidades do documento fotográfico, analisamos a ferramenta Sepiades, desenvolvida pelo CIA para descrever coleções fotográficas, atendendo às normas arquivísticas. Através da análise das duas ferramentas, realizada por meio de pesquisa bibliográfica e documental, verificamos que o AtoM é a ferramenta mais indicada para a descrição dos documentos. Como resultado, geramos um quadro para descrição de documentos fotográficos arquivísticos com base no AtoM, compatibilizado com os parâmetros do modelo Sepiades. / In archival institutions, images are increasingly accessible through the web. The research analyzes the description of digital photographic documents in this context, whether they are products of physical image scanning, that is, produced in analogical processes, or of digital-born images. It aims to analyze access in virtual environments, through the standardization of the norms of archival description. For this purpose, AtoM was used, software developed by the International Archive Council (CIA), a web-based tool that follows the standards of archival standards such as ISAD(G). In order to complement the specificities of the photographic document, we analyzed the Sepiades tool, developed by the CIA to describe photographic collections, meeting archival standards. Through the analysis of the two tools, carried out through bibliographical and documentary research, we verified that the AtoM is the most suitable tool for the description of the documents. As a result, we generated a framework for describing archival photographic documents based on AtoM, compatible with the parameters of the Sepiades model

The main focus of this project was to prepare transparent and conductive electrodes (TCEs). TCEs were made out of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), and polyvinylpyrrolidone (PVP). Based on the theoretical aspect, MWCNTs has emerged as a promising nanofiller in the polymer matrix due to its high electrical conductivity. As a nanofiller, MWCNTs were used with a small ratio of rGO with PVP as a polymer matrix in this project to prepare TCEs having low sheet resistance with high transparency. An appropriate amount of PVP has been shown to be a good combination with MWCNTs and rGO in the solvent to keep MWCNTs dispersed for a long time. Carboxyl group (-COOH) functionalized MWCNTs (FMWCNTs) was produced in a controlled oxidative procedure due to enabling good dispersion of FMWCNTs in water and ethanol solvents. In contrast, water dispersible rGO was chemically prepared by using GO and sodium borohydride where GO was produced from graphite by using improved Hummer's method. Drop casting and spray coating methods were applied to fabricate TCEswhere only water was used as the solvent for drop casted TCEs and a mixing ratio of water and ethanol was 70:30 as solvent for spray coated TCEs. It was also determined in this project that the spray coating method was more suitable for preparing TCEs rather than thedrop casting method due to easy fabrication, large area coating possibility, and the smoothness of the coated film surface. The sheet resistance was obtained as 5026 Ω/ ⃣  where the transparency was 65% in the case of the drop casted electrode for the ratio of rGO:FMWCNTs:PVP was 1.2:60:1 with 0.02 mg FMWCNTs. In the case of spray coated electrode at the same ratio of rGO:FMWCNTs:PVP, the sheet resistance was measured as 5961 Ω/ ⃣  where the transparency was 73%. But in the case of 60:1 mass ratio of FMWCNTs:PVP with 0.02 mg FMWCNTs, the sheet resistance was 7729 Ω/ ⃣  and transparency was 77% for spray coated electrode. So, it is clear that the sheet resistance was improved by adding a small mass ratio of rGO with FMWCNTs:PVP.