MARQUES, Maria Géssica Silva. Síntese e caracterização de bisbipiridinas de Ru com potencial aplicação como sensibilizadores de células solares. 2016. 52 f. Dissertação (Mestrado em Química)-Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Jairo Viana (jairo@ufc.br) on 2017-07-27T20:27:37Z No. of bitstreams: 1 2016_dis_mgsmarques.pdf: 1592936 bytes, checksum: dcfb887fb7a75bf5dacb583b97484368 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-07-27T20:27:53Z (GMT) No. of bitstreams: 1 2016_dis_mgsmarques.pdf: 1592936 bytes, checksum: dcfb887fb7a75bf5dacb583b97484368 (MD5) / Made available in DSpace on 2017-07-27T20:27:53Z (GMT). No. of bitstreams: 1 2016_dis_mgsmarques.pdf: 1592936 bytes, checksum: dcfb887fb7a75bf5dacb583b97484368 (MD5) Previous issue date: 2016 / In this work ruthenium bipyridine complexes of the type cis-[Ru(dcbpy)2(L)(L’)] (where dcbpy is 2,2-bipyridine-4,4-dicarboxylic acid; L is nicotinamide (nic) or isonicotinamide (isn) and L’ is Cl or SCN or nic) were synthesized and their electrochemical and photophysical properties were evaluated in order to verify their potential application as dye sensitizers in Dye Sensitized Solar Cells (DSSCs). These compounds were characterized by spectroscopic and electrochemical techniques. These complexes show metal-to-ligand charge transfer (MLCT) absorption centered at about 500 nm.Also, the compounds exhibit broad bands with maxima at 650 nm and low emission quantum yields. The result of cyclic voltammetry shows a redox couple at approximately 0.8 V vsAg/AgCl, which is positively shifted in comparison with the starting compound (~0.50V vs Ag/AgCl). The excited state oxidation potentials of both complexes (~ 1.5 V) are favorable for an efficient electron injection from the dye into the TiO2 conduction band.The photoelectrochemical data were evaluated in comparison to the standard [Ru(dcbH2)2(NCS)2] dye, N3. DSSCs sensitized by these compounds exhibit overall efficiency conversion of 0.38 and 0.47% for cis-[Ru(dcbpy)2(nic)Cl]+ and cis-[Ru(dcbpy)2(isn)Cl]+, respectively, while that for N3 is 2.70 % in the same condition. The lower adsorption and the higher charge recombination between the electrons injected into the TiO2 conduction band and oxidized dye molecules in comparison to N3 justify the lower global efficiencies observed than the N3 compound. / Neste trabalho foram sintetizados complexos bipiridinícos de rutênio (II) do tipo cis-[Ru(dcbpy)2(L)(L’)], onde dcbpy = ácido 4,4’-dicarboxílico-2,2’ bipiridina; L = nicotinamida (nic) ou isonicotinamida (isn) e L’= Cl ou SCN ou nic e suas propriedades eletroquímicas e fotofísicas foram avaliadas a fim de se comprovar sua estrutura esperada e seu potencial para atuar como corantes sensibilizadores em células solares sensibilizadas por corantes (do inglês Dye Sensitized Solar Cells,DSSCs). Tais complexos foram caracterizados por técnicas espectroscópicas e eletroquímicas. Os complexos apresentaram em seus espectros de absorção eletrônica na região do ultravioleta-visível bandas de transferência de carga do metal para o ligante com altos coeficientes de extinção molar na região do visível em cerca de 500 nm. Os compostos cis-[Ru(dcbpy)2(nic)Cl]+ e cis-[Ru(dcbpy)2(isn)Cl]+apresentaram em metanol uma emissão máxima em 650 nm com rendimento quânticos de da ordem de 0,0040.Os resultados eletroquímicos de voltametria cíclica para o par redox Ru (II/III) em ~0,80V vs Ag/AgCl, encontram-se deslocados positivamente em ao composto de partida (~0,50V vs Ag/AgCl). O potencial dos complexos no estado excitado, em torno de -1,5 V, indicam que os mesmos possuem capacidade de injetar elétrons na banda de condução do semicondutor TiO2. Os resultados dos testes fotovoltaicos para os complexos cis-[Ru(dcbpy)2(nic)Cl]+ e cis-[Ru(dcbpy)2(isn)Cl]+ apresentaram uma eficiência de conversão de energia de 0,38 e 0,47% respectivamente. A menor adsorção dos compostos contendo os ligantes nicotinamida e isonicotinamida em relação ao composto N3 e a ocorrência de recombinação de carga entre os elétrons injetados tanto com o corante oxidado quanto com o eletrólito justificam os menores valores de eficiência observados.

In this work, the possibility of Cu electrodeposition on Ru-Ta alloy thin films is explored. Ru and Ta were sputter deposited on Si substrate with different composition verified by RBS. Four point probe, XRD, TEM and AFM were used to study the properties of Ru-Ta thin films such as sheet resistance, crystallinity, grain size, etc. Cyclic voltammetry is used to study the Cu electrodeposition characteristics on Ru-Ta after various surface pretreatments. The results provide insights on the removal of Ta oxide such that it enables better Cu nucleation and adhesion. Bimetallic corrosion of Cu on modified Ru-Ta surface was studied in CMP related chemicals. In Cu interconnect fabrication process, the making of trenches and vias on low-k dielectric films involves the application of fluorocarbon plasma etch gases. Cu microdots deposited on Ru and Ta substrate were treated by fluorocarbon plasma etch gases such as CF4, CF4+O2, CH2F2, C4F8 and SF6 and investigated by using x-ray photoelectron spectroscopy, contact angle measurement and electrochemical techniques. Micropattern corrosion screening technique was used to measure the corrosion rate of plasma treated Cu. XPS results revealed different surface chemistry on Cu after treating with plasma etching. The fluorine/carbon ratio of the etching gases results in different extent of fluorocarbon polymer residues and affects the cleaning efficiency and Cu corrosion trends.

Since the dawn of the nuclear age, radioactive technetium (Tc)-99 has been released into the environment from nuclear weapons testing, spent fuel reprocessing facilities, and other nuclear activities. Quantifying the measurement, effect, and risk of trace concentrations of Tc-99 is paramount to understanding the isotope’s behaviour in human-environment systems. Ground state Tc-99 decays by beta emission (Emax — 292 keV) with a half-life (t1/2= 2.11 x 105 y), while the metastable isomer Tc-99m (t1/2 = 6.0 h) decays rapidly by emitting a gamma photon. Technetium-99 is present in the environment in mobile pertechnetate (TcO4−) form. Tc-99 is used as an oceanographic tracer to investigate seawater movement and coastal pollution using seaweed as a bioindicator. The purpose of this study is to develop a sample preparation method to measure low concentrations, down to femtogram levels, of Tc-99 in environmental samples such as seaweed, water and medical Tc-99m waste using an accelerator mass spectrometer (AMS). When present in its soluble form, Tc (VII)can be reduced to Tc (IV) in the presence of a strong reducing agent such as SnCl2, then precipitated out of solution as an iron hydroxide by the addition of an iron carrier. Using AMS to measure precipitates prepared through a simple one-step co-precipitation method show high levels of isobaric interferences by Ruthenium-99 (Ru-99) and impurities by the co-precipitation of other hydroxides. A double-step co-precipitation method was determined to be efficient at reducing interferences of impurities present in the final precipitate. Using Tc-99m as a chemical tracer, the efficiencies of different oxidizing- reducing agents were compared to optimize the yield of Tc-99. The aims and objectives of the study are first: to develop a method for the separation and purification of Tc-99 from Ru-99 by ARS-II with ABEC column. Second: to develop methods for the removal of interferences and extraction of Tc-99 from iii environmental small size samples, and third: to develop a method to analyze Tc-99 by low energy AMS. Concentrations of Tc-99 were measured in seaweed samples with a newly developed oxidation-reduction method using Tc-99m as a yield tracer. The detection of Tc-99 from seaweed samples follows a two-step procedure. The first step is the oxidation of technetium from Tc (IV) to Tc (VII) oxidation state with H2O2 followed by iron hydroxide precipitation. The second step is the reduction of Technetium from Tc (VII) to the Tc (IV) oxidation state with SnCl2 followed by iron hydroxide co-precipitate. The co-precipitate contains the Tc (IV) and is dried at 80oC and then at 200oC to remove excess water, then mixed with PbF2 to produce TcF5– in the AMS ion source. The purification and separation of Ru-99 from Tc-99 is done by ARS-II with ABEC column and measure by AMS. Currently, the most sensitive practical choice for Tc-99 is ICP-MS, with typical LOD at picogram (pg.) levels. This translates to 10-100s of litres required for a seawater sample. AMS has shown potential <10 fg LOD, which translates to volume requirement of sub-litre to litres for seawater samples, this would make the AMS quantification of Tc-99 an incredibly useful and competitive alternative.

This work is concentrated on the thermodynamic and kinetic aspects of water, alcohols, alkyl halides, ethers, and lactones bound and activated by the electrophilic [Cp'Ru(N0)] +2 and [Cp’Ru (NO)(CH3)] + centers (Cp' = cyclopentadienyl group). Counterions in these systems include OSO2CF3- (OTf-) and [(3, 5-(CF3)2C6H3)4B]- ([BAr4']-). The displacement of OTf- in Cp'Ru(N0) (0Tf)2 by H20 in dichloromethane is exothermic but entropically unfavorable due to the required reorganization of the solvent cage around released triflate ions. Thermodynamic parameters are also determined for OTf displacement by chloride and tetrahydrofuran (THF) using the 19F nuclear magnetic resonance (NMR) spectroscopy. The conversion of the [Cp’Ru (NO)(OH2)2] +2 to [Cp’Ru (NO)(μ-OH)} 2 +2 in aqueous solutions is characterized thermodynamically and kinetically by potentiometric and NMR methods. The results of the study of rhodium triflato complex trans- [Rh (CO)(PPh3)2(OTf)] show that OTf coordinates to the metal center in wet dichloromethane solutions, but the compound crystallizes as a water-coordinated triflate salt trans- [Rh (CO)(PPh3)2(OH2)] [OTf]. Thermodynamic parameters for alcohol (methanol, ethanol, isopropanol) binding to the Cp*Ru(N0) (0Tf)2 are determined from the 19F NMR spectroscopic data. The kinetics of the oxidation of alcohols to aldehydes or ketones via Ru (II) >>> Ru (0) redox process is studied by NMR methods. The results of the study support {3-hydrogen elimination mechanism, comprising one of the very few mechanistic investigations on reactions of this kind. Alkyl iodides are found to bind to the [Cp*Ru (NO)(CH3)] + fragment via displacement of a THF ligand in the presence of a BAr4 •-counterion, forming alkyl halide complexes that convert to [Cp’Ru (NO)(μ-I)]2+2. The mixed ruthenium-chromium complex [CpCr (NO)2(μ-I) (Ru (Cp’) (NOW is characterized as primarily a [Ru-I >> Cr] system as opposed to a [Ru << I-Cr] model. The complex [Cp*Ru (NO)(CH3) (THF)] is found to catalyze aerobic oxidation of THF to -y-butyrolactone. The new -y-butyrolactone ruthenium complex is isolated and characterized by X-ray methods in the solid state. The mechanism of catalytic oxidation is studied by 18O-labeled infrared spectroscopic methods. Radical decomposition of the intermediate hydroperoxy-tetrahydrofuran gives 1, 6-diol-diformate [CH(O)-(CH2)6-CH(O)]. The radical mechanism for the catalytic oxidation of THF is proposed.

The effect of RU 486 at different concentrations (1, 5, 10, and 20 µg/ml) was studied on sperm-egg interaction in vitro in B6D2Ff mice. The in vitro fertilization rate of mouse ova decreased from 77.0% (control) to 50.0%, 28.7%, and 7.5% in the presence of RU 486 concentrations at 5, 10, and 20 µg/ml medium, respectively (p < 0.001). A concentration of 1 µg/ml did not affect the fertilization rate. A progesterone concentration at equal to or double the concentration RU 486 did not reverse the inhibitory effect of RU 486 on in vitro fertilization, which suggests a progesterone-independent mechanism. Exposure of spermatozoa (for 90 minutes) or ova (for 60 minutes) to RU 486 (20 µg/ml) followed by washing with RU 486-free medium before coincubation did not affect the fertilization rate. The presence or absence of cumulus cells did not change the inhibitory effect of RU 466 (20 µg/ml) on in vitro fertilization. RU 486 at 5 to 20 µg/ml medium was associated with perivitelline polyspermy in nonfertilized ova and enhanced perivitelline polyspermy in fertilized oval.

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Aufgrund von guten Eigenschaften als Kupferdiffusionsbarriere und guter elektrischer Leitfähigkeit könnte sich Ruthenium und Ruthenium basierte Legierungen als Kupferdiffusionsbarriere eignen. Auf eine theoretische Aufarbeitung von Elektromigrationsmechanismen und in der Praxis eingesetzte Elektromigrationsteststrukturen folgen beschleunigte elektrische Elektromigrationstestergebnisse. Es konnte gezeigt werden, dass das System Kupfer, Ruthenium, Tantalnitrid Elektromigrationsstabiler als das konventionelle System Kupfer, Tantal, Tantalnitrid ist.:1 Einleitung 1 2 Stand der Forschung 2 2.1 Migrationsarten 2 2.2 Praktische Formulierung des Mechanismus der Elektromigration 2 2.3 Transportpfade der Elektromigration 3 2.4 Einflüsse auf die Elektromigration 4 2.4.1 Übersicht 4 2.4.2 Quereinfluss des mechanischen Stresses (Blech-Effekt) 5 2.4.3 Quereinfluss durch thermisch induziertem Stress 6 2.4.4 Materialwanderung aufgrund eines Temperaturgradienten 8 2.4.5 Einfluss des Leiterbahnmaterials (Legierung) 8 2.4.6 Einflüsse der Mikrostruktur 8 2.4.7 Einflüsse der Passivierung der Leiterbahnen 9 3 Theoretische Untersuchungen 9 3.1 Untersuchte Elektromigrationsteststrukturen 9 3.1.1 NIST-Struktur 9 3.1.2 Untersuchungen mithilfe der NIST-Struktur 10 3.1.3 Schlitz-Struktur 11 3.1.4 Bestimmung des Flächenwiderstandes RF = r=A der Schlitz-Struktur 12 3.1.5 Schlitzlängenänderungsgeschwindigkeit der Schlitz-Struktur 13 3.1.6 Prinzipielles Vorgehen zur Bestimmung der Schlitzlängenänderungsgeschwindigkeit als Kriterium für Elektromigrationsbeständigkeit 14 3.1.7 Blech-Struktur 15 3.1.8 Untersuchungen mithilfe der Blechstruktur 16 3.2 Vergleich der untersuchten Elektromigrationsteststrukturen 16 4 Experimentelle Untersuchungen 17 4.1 Beschreibung des Versuchsaufbaus 17 4.2 Evaluation der Messvorraussetzungen 18 4.2.1 Temperaturbeständigkeit der Messanordnungen 18 4.2.2 Oxidationsbeständigkeit der Schlitz- & Blechstruktur 19 4.2.3 Vernachlässigung Kupfer- und Leitungswiderstände 21 II 4.2.4 Untersuchungen bei verschiedenen Stromdichten (Schlitzstruktur) 22 4.2.5 Evaluation der günstigsten Schlitzlänge für Klassifikationstests 24 4.3 Untersuchungen an der NIST-Struktur 26 4.3.1 Ergebnisse 26 4.3.2 Probleme beim Versuchsaufbau und mögliche Lösungen 27 4.4 Untersuchungen an der Schlitz-Struktur 28 4.4.1 Bestimmung des Flächenwiderstands RF 28 4.4.2 Bestimmung der Schlitzlängenänderungsgeschwindigkeit 28 4.4.3 Optische Probenauswertung mittels TEM und FIB-Schnitt 30 4.4.4 Vergleich von Ta mit Ru und Ru0;95Mn0;05 31 4.4.5 Probleme beim Messaufbau und mögliche Lösungen 31 4.5 Untersuchungen an der Blechstruktur 33 4.5.1 Untersuchungen bei verschiedenen Stromdichten 33 4.5.2 Untersuchung bei verschiedenen Temperaturen 35 4.5.3 Probleme bei den Messungen und mögliche Lösungen 36 5 Zusammenfassung 37 6 Literaturverzeichnis 38

L'effet tunnel dépendant du spin dans une structure métal ferromagnétique/isolant/métal ferromagnétique, composant une jonction tunnel magnétique, connaît ces dernières années un regain d'intérêt avec sa mise en évidence à température ambiante et avec ses multiples applications potentielles pour l'élaboration de nouveaux dispositifs micro-électroniques (mémoires non-volatiles, capteurs magnéto-résistifs, etc). Dans une jonction tunnel magnétique la transmission par effet tunnel des électrons, polarisés par les électrodes magnétiques, dépend de l'orientation relative des aimantations des électrodes et des caractéristiques de la barrière isolante. La résistance d'une jonction tunnel magnétique varie de plus de 20% en modifiant de manière sélective l'orientation de l'aimantation d'une électrode par rapport à l'autre, en appliquant un champ. Pour cela, une architecture appelée douce-dure est utilisée. Elle repose sur l'association d'une couche magnétique dure et d'une couche magnétique douce comme électrodes magnétiques de la jonction tunnel. Un aspect novateur de ce travail de thèse repose sur l'utilisation d'un système antiferromagnétique artificiel comme système magnétique dur. Ce système, constitué de deux couches magnétiques (Co et/ou CoFe) d'épaisseurs différentes, ayant leurs aimantations arrangées antiparallèles par couplage à travers une couche non magnétique (Ru), permet d'obtenir une grande rigidité magnétique, ajustable, avec une grande stabilité thermique (>300°C). Ce travail de thèse nous a amené à élaborer des jonctions tunnel magnétiques de taille micronique et à étudier la corrélation entre leurs propriétés magnétiques et leurs propriétés de transport polarisé en spin à des échelles macroscopiques et microscopiques. Il s'est avéré que, grâce à la sensibilité extrême du transport par effet tunnel polarisé en spin aux fluctuations de l'aimantation aux interfaces métal ferromagnétique/isolant, les jonctions magnétorésistives sont des systèmes idéaux pour étudier sélectivement l'évolution de la structure en domaines des couches ferromagnétiques en contact avec la couche isolante en fonction du champ magnétique appliqué.

Made available in DSpace on 2015-03-03T15:28:30Z (GMT). No. of bitstreams: 1 CarlosAGS_DISSERT.pdf: 446797 bytes, checksum: 18c0fd9fe8336f2abf045fa977920e6c (MD5) Previous issue date: 2010-03-19 / In this work, we present a risk theory application in the following scenario: In each period of time we have a change in the capital of the ensurance company and the outcome of a two-state Markov chain stabilishs if the company pays a benece it heat to one of its policyholders or it receives a Hightimes c > 0 paid by someone buying a new policy. At the end we will determine once again by the recursive equation for expectation the time ruin for this company / Neste trabalho, apresentamos uma aplica??o da teoria do risco com o seguinte cen?rio: as mudan?as no capital de uma seguradora acontecem em cada instante de tempo e o pagamento de uma indeniza??o ou recebimento de um pr?mio ? decidido pelo resultado de uma cadeia de Markov de dois estados. Nesta situa??o calculamos a probabilidade de ru?na e o tempo esperado de ru?na quando o valor da indeniza??o ? um m?tiplo do valor do pr?mio