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Optické a magnetooptické vlastnosti Heuslerových sloučenin / Optical and magneto-optical properties of Heusler compoundsKrál, Daniel January 2017 (has links)
Cílem této práce bylo studium Heuslrových sloučenin pomocí optických a magneto-optických (MO) metod. V případě první sloučeniny, Co2FeGa0.5Ge0.5, jsme studovali výskyt strukturálního disorderu za pomoci spektroskopické elipsometrie, MO spektroskopie a MO Kerrovy magnetome- trie. Experimentální výsledky jsme poté porovnali s teoretickými modely. Doplnili jsme také výsledky našich spolupracovník·, a to včetně X-ray difrakce, atomic-force mikroskopie a ab initio výpočt·, abych potvrdili naši interpretaci naměřených výsledk·. Bylo zjištěno, že strukturální disorder je vskutku pozorovatelný pomocí metod, kterých jsme využili. Jeho výskyt se projevil změnou elektronové struktury vzork·. V případě druhé sloučeniny, Fe2MnGa, jsme vyšetřovali vliv obsahu Fe složky na optické a MO vlastnosti tohoto materiálu. Zjistili jsme, že atomy Fe ovlivňují koncentraci volných elektron·, čímž dodávají sloučenině kovový charakter (v porovnání s Ni2MnGa). Zároveň zvyšují optickou a MO odezvu v blízké infra-červené oblasti spektra. Dále bylo zjištěno, že vzorek s nejvyšším obsahem Fe má nulovou magnetizaci. 1
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Development of a femtosecond time-resolved spectroscopic ellipsometry setupHerrfurth, Oliver 26 July 2019 (has links)
The developement of a femtosecond-time-resolved spectroscopic ellipsometry setup based on a pump-probe technique is described. The characterization of the setup is presented as well as first results of experiments on a c-plane oriented ZnO thin film are shown. Indications for the study of fast charge-carrier dynamics are given.:Introduction 1
1 Theoretical framework 3
1.1 Zinc oxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1 Crystal and band structure . . . . . . . . . . . . . . . . . . . . . 3
1.1.2 Excitons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Dielectric function and electronic transitions . . . . . . . . . . . . . . . . 5
1.2.1 Electronic transitions . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.2 Dielectric function . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Charge carrier dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.1 High excitation effects . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.2 Charge carrier density-dependent dielectric function model . . . . 9
1.4 Light polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2 Preliminary experiments 14
2.1 Methods and instrumentation . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.3 Experimental challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.4.1 Time-integrated micro-ellipsometry . . . . . . . . . . . . . . . . . 28
2.4.2 Time-resolved ellipsometry . . . . . . . . . . . . . . . . . . . . . . 31
2.4.3 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3 Conclusive experiments at ELI Beamlines 35
3.1 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2 Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.3 Demonstration of functionality . . . . . . . . . . . . . . . . . . . . . . . . 49
3.3.1 Time-resolved reflectometry . . . . . . . . . . . . . . . . . . . . . 49
3.3.2 Time-resolved ellipsometry . . . . . . . . . . . . . . . . . . . . . . 51
4 Results and discussion 55
4.1 Time-resolved reflectometry . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.2 Time-resolved ellipsometry . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5 Summary and outlook 63
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Bioimpedanční spektroskopická analýza kompozice těla v době laktace. / Bioimpedance spectroscopic body analysis during lactation.Urbánková, Tereza January 2020 (has links)
The aim of the diploma thesis was to cover the changes in body composition by bioimpedance spectroscopy in Czech breastfeeding women during three periods - 3 weeks postpartum, 3 months and 6 months postpartum. Eight healthy breastfeeding women were involved in the study. At each examination there were measured anthropometric parameters and bioimpedance spectroscopy parameters by the Body Composition Monitor. Breast milk was also extracted during the study. We observed a gradual decrease in body weight of monitored women. The median weight loss between the first and third examination was 2,2 kg, the median weight in 6 months postpartum was 1,3 kg higher than the median of prepregnancy body weight, two of the women had lower weight 6 months postpartum than before the pregnancy, the body weight of other six women was higher in a scale between 0,1 kg to 3,1 kg. There were not proven statistically significant differences in body composition during lactation. A trend of decrease of TBW was observed during all lactation periods. A trend of slight increase of ICW was observed between the 3rd week and 3rd month postpartum, and then the decrease of ICW in the 6th month postpartum. An increase of LTM and BCM was measured between the 3rd week and 3rd month postpartum, those values have shown a decrease again...
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Probing the Strongly Correlated Quantum Materials with Advanced Scanning Tunneling Microscopy/Spectroscopy:Zhao, He January 2020 (has links)
Thesis advisor: Ilija Zeljkovic / We used spectroscopic-imaging scanning tunneling microscopy (SI-STM) and spin-polarized STM (SP-STM) to unveil new electronic phenomena in several different quantum systems. We explored: (1) a potential topological superconductor heterostructure Bi₂Te₃/Fe(Te, Se), (2) high-Tc superconductors − Bi₂Sr₂CaCu₂O₈₊ₓ and Fe(Te, Se), and (3) doped spin-orbit Mott insulators Sr₂IrO₄ and Sr₃Ir₂O₇. In Bi₂Te₃/Fe(Te, Se), we observed superconductivity (SC) on the surface of Bi₂Te₃ thin film, induced by the iron-based superconductor substrate. By annealing the optimally-doped cuprate superconductor Bi₂Sr₂CaCu₂O₈₊ₓ, we drastically lowered the surface hole doping concentration to detect a unidirectional charge stripe order, the first reported charge order on an insulating (defined by the spectral gap with zero conductance spanning the Fermi level) cuprates surface. In the high-Tc SC Fe(Te, Se) single crystal, we found local regions of electronic nematicity, characterized by C₂ quasiparticle interference (QPI) induced by Fermi surface anisotropy and inequivalent spectral weight of dyz and dxz orbitals near Fermi level. Interestingly, the nematic order is locally strongly anti-correlated with superconductivity. Finally, utilizing SP-STM, we observed a short-range antiferromagnetic (AF) order near the insulator-metal transition (IMT) in spin-orbital Mott insulators Sr₂IrO₄ and Sr₃Ir₂O₇. The AF order inhomogeneity is found not to be strongly correlated with the charge gap. Interestingly, the AF order in the bi-layered Sr₃Ir₂O₇ shows residual memory behavior with temperature cycling. Overall, our work revealed new phenomena in a range of today’s most intriguing materials and set the stage for using SP-STM in other complex oxides. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.
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Nanopartículas de hexacianoferrato (ii) de cério (iii) em meio água/formamida e sua aplicação na eletro-oxidação catalítica da l-dopamina /Oliveira, Denys Ribeiro de January 2019 (has links)
Orientador: Devaney Ribeiro do Carmo / Resumo: Neste trabalho esta descrito a preparação de nanopartículas de Hexacianoferrato (II) de Cério (III) (NpsCe), em quatro proporções diferentes de solventes a saber: Água/Formamida (100:0; 80:20; 40:60; 0:100), afim de se investigar a influência dos solventes no tamanho, morfologia, nas propriedades físico-químicas, voltamétrica e eletrocatalíticas da NpsCe. As Nps foram caracterizadas pelas técnicas de Espectroscopia na Região do Infravermelho (FTIR), Difração de Raios-X (DRX), Microscopia Eletrônica de Varredura (MEV), Potencial Zeta, Voltametria Cíclica (VC) e Voltametria de Pulso Diferencial (VPD). Dos quatro sistemas estudados apenas o CeHCF-1 (100/0) e o CeHCF - 3 (40/60) se apresentaram sensíveis a concentrações do neurotransmissor L-dopamina permitindo a confecção de uma curva de calibração. O sistema CeHCF-1 apresentou duas regiões linerares de sinal em função da concentração de L-dopamina, com limite de detecção (LD) de 0,125 mmol L-1 e 0,023 mmol L-1 obtido pelas técnicas de VC e VPD, respectivamente. Para o sistema CeHCF-3 observou-se por VC uma região linear de intensidade de corrente anódica e a concentração de L-dopamina com LD de 0,0317 mmol L-1, já por VPD apresentou duas regiões lineares de sinal em função da concentração de L-dopamina, com LD de 1,98 x 10-4 e 0,0104 mmol L-1. O sistema CeHCF – 3 apresentou promissor a detecção e quantificação de DA em amostras reais. Assim realizou-se o estudo para avaliar a seletividade deste frente a substâncias comumente en... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work is rearmed to nanoparticles of Cerium (III) Hexacyanoferrate (II) (NpsCe) analog of PB in four different proportions of Water / Formamide solvents (100: 0, 80:20, 40:60, 0: 100 ), to investigate the influence of solvents on the size, morphology, physicochemical, electrochemical and electrocatalytic properties of NpsCe. The Nps were characterized by the techniques of Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Zeta Potential, Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV). Of the four systems studied, only CeHCF-1 (100/0) and CeHCF-3 (40/60) are formed in small concentrations of the neurotransmitter L-dopamine. The CeHCF-1 system showed two signal regions as a function of L-dopamine concentration, with detection limit (LD) of 0.125 mmol L-1 and 0.023 mmol L-1 given by the CV and DPV techniques, respectively. For the CeHCF-3 system it can be seen as a linear signal region as a function of the L-dopamine concentration by the CV technique with LD of 0.0317 mmol L-1, or by DPV through two linear signal regions in the function of the concentration of L-dopamine, with LD of 1.98 x 10-4 and 0.0104 mmol L-1. The launched CeHCF – 3 system promises to detect and quantify DA in real cases. Thus, a study was carried out to reduce the resistance of a substance found in the physiological industries that have the potential of oxidation and reduction of the DA. Substantial subtranslators studied here were Urea and Asco... (Complete abstract click electronic access below) / Mestre
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Studium tenkých mazacích filmů spektroskopickou reflektometrií / THIN LUBRICANT FILMS STUDY USING SPECTROSCOPIC REFLECTOMETRYČudek, Vladimír January 2010 (has links)
ectroscopic reflectometry is measurement technique that enables the study of the thickness and refractive index of thin layers. This thesis deals with its use for the study of lubrication films within EHD contact and verifies a new approach suggested in recent publications. It is focused on the development of an optical arrangement and mathematical model for the lubrication film thickness measurement within the entire EHD contact. This technique brings the possibility to study the pressure distribution within the contact area through the evaluation of changes in lubricant refractive index.
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A Study on Plasma Process-Induced Damage during Fabrication of Si Devices and Methodology for Optical Measurement / Siデバイス製造過程におけるプラズマプロセス誘起ダメージとその光学的測定方法論の研究Matsuda, Asahiko 23 May 2013 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17788号 / 工博第3767号 / 新制||工||1576(附属図書館) / 30595 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 斧 髙一, 教授 木村 健二, 教授 立花 明知 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
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A study of defect generation phenomena in single crystalline silicon substrate during plasma processing and the characterization techniques / プラズマ暴露によるシリコン単結晶基板中の欠陥生成メカニズム及びその評価技術の研究Nakakubo, Yoshinori 25 May 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19185号 / 工博第4062号 / 新制||工||1627(附属図書館) / 32177 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 斧 髙一, 教授 木村 健二, 教授 立花 明知 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
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Application of Techniques in Spectroscopic Ellipsometry for Analysis of the Component Layers in CdTe Solar CellsAlaani, Mohammed A. Razooqi 11 July 2022 (has links)
No description available.
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Optical Properties of Rydberg Excitons in Cuprous OxideJacob C DeLange (15209836) 12 April 2023 (has links)
<p>Cuprous oxide (Cu<sub>2</sub>O) has recently been proposed as a promising solid-state host for ex-<br>
citonic Rydberg states with large principal quantum numbers (n) whose exaggerated wave-<br>
function sizes (∝ n<sup>2</sup>) facilitate gigantic, resonant dipole-dipole (∝ n<sup>4</sup>) and van der Waals<br>
(∝ n<sup>11</sup>) interactions, making them an ideal basis for solid-state Rydberg physics and quan-<br>
tum technology. Synthetic, thin-film Cu<sub>2</sub>O samples are of particular interest because they<br>
can be made defect-free via carefully controlled fabrication and are, in principle, suitable<br>
for the observation of extreme single-photon nonlinearities caused by Rydberg blockade. In<br>
this work, we present the development of a spectroscopy experiment for characterizing the<br>
behavior of Rydberg excitons and use it to study a synthetic thin film of Cu<sub>2</sub>O grown on a<br>
transparent substrate. We present evidence for the presence of states up to n = 8 and conduct<br>
the first temperature-dependent study of Rydberg excitons in a thin film. We also propose<br>
a technique for studying Rydberg-Rydberg interactions via the creation of high exciton den-<br>
sities and establish a set of rate equations for modeling the processes by which excitons are<br>
created, interact with each other, and decay. Finally, we conclude with a discussion of the<br>
project’s outlook, as well as what future work will be undertaken to study the interactions<br>
between Rydberg excitons and utilize them in scalable, integrable, Rydberg-based quantum<br>
devices.<br>
</p>
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