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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Colloidal Synthesis and Optical Characterizations of Semiconductor Nanocrystals from Nontoxic Elements

Ho, Minh Q 01 January 2015 (has links)
To date, the search efforts have shifted from the toxic II-VI, III-V and IV-VI semiconductors to more environmentally friendly materials. Among Group II-V semiconductors, Zn3P2 has shown to be a more benign option, similar to Group IV (Ge, Si) materials, for future applications in photovoltaics and optoelectronics. This work is dedicated to the development of wet-chemical synthetic routes of (1) Zn3P2 and (2) Group IV (Ge, Si, Si1-xGex) nanocrystals with precise control over composition, crystal structure, size and dispersity by adjusting different reaction parameters such as temperature, time and solvent composition. Different characterizations will also be employed to probe the size- and composition-dependent physical and optical properties of resulting products. The first part of this work illustrates the synthesis of luminescent Zn3P2 nanocrystals, an earth-abundant and a direct-gap semiconductor possessing high absorption coefficient and long carrier diffusion length, which uphold promising potential in many optoelectronic applications. A hot injection method by using highly reactive P and Zn precursors (P[Si(CH3)3]3 and diethyl zinc) in hexadecylamine and octadecene was developed to prepare a series of alkyl-amine-passivated tetragonal Zn3P2 crystallites with varying size sizes. Substantial blue shifts in the absorption onsets (2.11−2.73 eV) in comparison to the bulk counterpart (1.4−1.5 eV) and a clear red shift with increasing particle size indicates the quantum confinement effects. This is also consistent with the photoluminescent studies with the size-tunable maxima in the visible region (469−545 nm) as a function of growth temperature and time. The phase purity and alkyl-amine passivation of the nanocrystals were determined by structural and surface analysis, confirming the presence of N–Zn and N–P bonds on the tetragonal Zn3P2 crystallites. The second part of this works focuses on the development of a colloidal synthetic strategy of alkyl-amine capped Si1-xGex nanocrystals with control over size- and composition-dependent optical properties. Despite their high miscibility at all compositions, developing a wet-chemical synthesis of Si1-xGex alloys in the nanoscale remains a challenging task, owing to the difference of their crystallization temperatures and the high surface oxidation of Si. Thus an adapted colloidal method is utilized to fabricate single-element Ge and Si nanocrystals. Powder X-ray diffraction indicates successful production of cubic crystalline Ge and amorphous Si nanoparticles individually in oleylamine/octadecene (surfactant/solvent) mixture at 300°C. Absorption onset values of 1.28 eV and 3.11 eV are obtained for resulting Ge and Si colloids, respectively. By alloying these two materials in their nano-regime, tunable optical properties can be achieved throughout the visible to the near IR region by simply varying their elemental compositions. The success of this bandgap engineering process offers more options for new material design by taking advantage of unique properties from each component material.
12

Síntese e caracterização do core-shell ZrO2:Y3+@TiO2 / Synthesis and characterization of core-shell ZrO2:Y3+@TiO2

Silva, P. D. G. 21 March 2016 (has links)
Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-10-27T16:02:50Z No. of bitstreams: 2 Dissertação - Paula Daiany Gonçalves Silva - 2016.pdf: 5020325 bytes, checksum: 7a70eccab776cc3598c1f6236a35273d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-11-07T13:53:03Z (GMT) No. of bitstreams: 2 Dissertação - Paula Daiany Gonçalves Silva - 2016.pdf: 5020325 bytes, checksum: 7a70eccab776cc3598c1f6236a35273d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-11-07T13:53:03Z (GMT). No. of bitstreams: 2 Dissertação - Paula Daiany Gonçalves Silva - 2016.pdf: 5020325 bytes, checksum: 7a70eccab776cc3598c1f6236a35273d (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Since the early 90's researchers have investigated the combination of nanocomposites comprised of multilayers, which have better efficiency than their corresponding individual particles, may present in certain cases, new properties. The resulting structure is called a core-shell. In this study, were synthesized ZrO2:Y 3+ coated with TiO2, obtaining nanocomposites ZrO2:Y 3+ @TiO2 with a thickness of 10, 20 and 50% shell. The photoluminescent property (FL) of the nanocomposites was studied. Such interest is due to the fact that the order/disorder structural at the interface of the core-shell type systems may be possible recombination processes responsible for the photoluminescence emission of these materials. Nanoparticles of the core and the shell were obtained by the Method of Polymeric Precursors. The samples were characterized by X-ray diffraction (XRD) to identify the formation of the nanocomposite and evaluate the structural order in the synthesized materials. The core was obtained with tetragonal structure and the shell with anatase structure. From the diffractograms have been carried out calculations of the crystallite size and lattice parameters. The characterization by Transmission Electron Microscopy (TEM), it was not possible to differentiate the core of the shell by the images, since both are structurally ordered, requiring analysis by Energy Dispersive X-ray (EDX), which was verified the presence of Zr and Ti elements that comprise the core-shell nanocomposite. The FL emission results were explained as a function of the shell thickness, as well as the effect of calcination temperature on the order-disorder structural material. To evaluate the performance of the FL issuing nanocomposites were calculated chromaticity coordinates, based on the FL emission spectra. / Desde o início da década de 90 pesquisadores vêm investigando a combinação de nanocompósitos constituídos por multicamadas, os quais apresentam melhor eficiência do que suas partículas individuais correspondentes, podendo apresentar em alguns casos, novas propriedades. A estrutura obtida é denominada core shell. No presente trabalho, foram sintetizados ZrO2:Y 3+ recobertos com TiO2, obtendo nanocompósitos ZrO2:Y 3+ @TiO2 com espessura de 10, 20 e 50% de shell. Foi estudada a propriedade fotoluminescente (FL) dos nanocompósitos. Tal interesse deve-se ao fato de que a ordem/desordem estrutural na interface dos sistemas do tipo core-shell pode ser possibilitar processos de recombinação responsáveis pela emissão fotoluminescente destes materiais. As nanopartículas do core e do shell foram obtidos pelo Método dos Precursores Poliméricos. As amostras foram caracterizadas por difração de Raios X (DRX) a fim de se identificar a formação do nanocompósito e avaliar a ordem estrutural nos materiais sintetizados. O core foi obtido com estrutura tetragonal e o shell com estrutura anatase. A partir dos difratogramas foram realizados cálculos do tamanho de cristalito e parâmetros de rede. Na caracterização por Microscopia Eletrônica de Transmissão (MET), não foi possível diferenciar o core do shell pelas imagens, uma vez que ambos encontram-se estruturalmente ordenados, sendo necessária a análise por Energia Dispersiva de Raios X (EDX), na qual verificou-se a presença dos elementos Zr e Ti que compõem o nanocompósito core-shell. Os resultados de emissão FL foram explicados em função da espessura do shell, bem como pelo efeito da temperatura de calcinação na ordem-desordem estrutural do material. Para avaliar o desempenho da emissão FL dos nanocompósitos foram calculadas as coordenadas de cromaticidade, baseado nos espectros de emissão FL.
13

Novos complexos de lantanídeos contendo ânions carboxilatos e ligantes nitrogenados: busca por novos dispositivos moleculares conversores de luz

Marques, Lippy Faria 27 March 2014 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-05-08T15:26:07Z No. of bitstreams: 1 lippyfariamarques.pdf: 22312576 bytes, checksum: 4211af206576435ad4b8e5af6c3c6abf (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T13:44:16Z (GMT) No. of bitstreams: 1 lippyfariamarques.pdf: 22312576 bytes, checksum: 4211af206576435ad4b8e5af6c3c6abf (MD5) / Made available in DSpace on 2017-05-17T13:44:16Z (GMT). No. of bitstreams: 1 lippyfariamarques.pdf: 22312576 bytes, checksum: 4211af206576435ad4b8e5af6c3c6abf (MD5) Previous issue date: 2014-03-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho aborda a síntese e caracterização de complexos de lantanídeos (III) contendo os ânions 2,5-tiofenodicarboxilato (2,5-tdc2-) e hidrocinamato (cin-) e o ligante nitrogenado 2,2’-bipiridina (bpy), com o intuito de investigar suas características químicas e estruturais e correlacioná-las com as propriedades fotoluminescentes. Duas séries de compostos obtidos com o ânion 2,5-tdc2- foram formuladas como: [Ln2(2,5-tdc)3(dmf)2(H2O)2]·2dmf·H2O (Ln = Dy (1), Tb (2), Eu (3), Gd (4), Er (5)), [Nd2(2,5-tdc)3(dmf)2(H2O)2]·dmf·H2O (7) e {[Ln2(2,5-tdc)3(dmso)2]·H2O}n ( Ln = Dy (8), Tb (9), Eu (10), Gd (11), Nd (12), Sm (13), Yb (14), Ho (15), Er (16), Tm (17), Pr (18)). Duas séries de compostos com o ligante cin- foram obtidas e formuladas como: [Ln(cin)3(H2O)3]·3Hcin (Ln = Dy (19), Tb (20), Eu (21), Er (22) e Gd (23)) e [Ln2(cin)6(bpy)2] ( Ln = Tb (24), Eu (25) e Gd (26)). Todos os compostos sintetizados foram caracterizados por análise elementar (CHN), análise térmica (TG/DTA), espectroscopia vibracional na região do infravermelho (IV), espectroscopia de reflectância difusa (RD) e difração de raios X (policristal e monocristal). O estudo de suas propriedades ópticas foi obtido a partir dos espectros de emissão e excitação e pela curva de decaimento luminescente. Com base nos dados espectrais foram determinados os parâmetros de intensidade experimentais (Ω2 e Ω4), coeficientes de emissão radiativa (Arad) e não – radiativa (Anrad) e a eficiência quântica de emissão (ɳ) do nível 5D0 do íon Eu(III). As estruturas cristalinas dos complexos (7), (8) e (9) foram determinadas através da técnica de difração de raios X por monocristal, demonstrando a formação de redes metalo – orgânicas de lantanídeos porosas (LnMOFs). A atribuição dos estados tripleto (T1) do ligante 2,5-tdc2- foi feita a partir dos espectros de emissão dos respectivos complexos de Gd(III) , mostrando a possibilidade de transferência de energia intramolecular nesses compostos. Todos os compostos contendo o ligante cin- (19)-(26) tiveram suas estruturas determinadas por difração de raios X por monocristal. Apesar da possibilidade de ocorrência do efeito antena nos compostos (19), (20) e (21), a presença de três moléculas de água diretamente coordenadas aos íons lantanídeos (III), promovem uma supressão da luminescência. Para o complexo [Eu2(cin)6(bpy)2] (25) foram obtidos os parâmetros de intensidades (Ω2, Ω4 e Ω6), taxas de decaimento radiativo (Arad) , não – radiativo (Anrad), transferência de energia (WET), retro – transferência de energia (WBT) e rendimento quântico. Esses dados se encontram em excelente acordo com dados experimentais com tal complexo possuindo uma eficiência quântica (ɳ) de 67%, sugerindo que esse sistema pode ser excelente para o desenvolvimento de dispositivos luminescentes. / The present work reports the synthesis and characterization of lanthanide (III) complexes containing 2,5-thiophenedicarboxylate (2,5-tdc2-) and hydrocinnamate (cin-) anions and nitrogen ligand 2,2’-bipyridine (bpy) in order to investigate its chemical and structural features and correlate with the photoluminescent properties. Two series of compounds obtained from the 2,5-thiophenedicarboxylate anion were formulated as: [Ln2(2,5-tdc)3(dmf)2(H2O)2]·2dmf·H2O (Ln = Dy (1), Tb (2), Eu (3), Gd (4), Er (5)), [Nd2(2,5-tdc)3(dmf)2(H2O)2]·dmf·H2O (7) and {[Ln2(2,5-tdc)3(dmso)2]·H2O}n ( Ln = Dy (8), Tb (9), Eu (10), Gd (11), Nd (12), Sm (13), Yb (14), Ho (15), Er (16), Tm (17), Pr (18)). Two series of compounds obtained from the cin- ligand were formulated as: [Ln(cin)3(H2O)3]·3Hcin (Ln = Dy (19), Tb (20), Eu (21), Er (22) e Gd (23)) e [Ln2(cin)6(bpy)2] ( Ln = Tb (24), Eu (25) e Gd (26)). All synthesized compounds were characterized by elemental analysis (CHN), thermal analysis (TG/DTA), vibrational spectroscopy in the infrared region (IR), reflectance diffuse spectroscopy (DR) and Xray diffraction (powder and single crystal). The study of their optical properties was obtained from the emission and excitation spectra and by the luminescent decay curve. Based on spectral data, the experimental intensity parameters (Ω2 and Ω4), radiative emission (Arad) and non-radiative (Anrad) coefficients and emission quantum efficiency (ɳ) of the 5D0 level the Eu(III) ion were determined. The crystal structures of complexes (7), (8) and (9) were determined using single crystal X-ray diffraction analysis, showing the formation of lanthanide (III) metal-organic porous frameworks (LnMOFs). The assignment of the triplet states (T1) of the 2,5-tdc2- ligand was taken from the emission spectra of the respective complexes of Gd(III), showing the possibility of intramolecular energy transfer in these compounds.All compounds containing the cin- ligand (19)-(26) had their structures determined by single crystal Xray diffraction analysis. Despite the possibility of the antenna effect of compounds (19), (20) and (21), the presence of three water molecules directly coordinated to lanthanide (III) ions, promotes the luminescence suppression. For [Eu2(cin)6(bpy)2] (25) complex, the intensity parameters (Ω2, Ω4 e Ω6), radiative decay (Arad), non-radiative (Anrad), energy transfer (WET), back energy transfer (WBT) rates and quantum efficiency were obtained. These data are in excellent agreement with experimental data with such complex having quantum efficiency (ɳ) of 67% suggesting that this system can be excellent for the development of luminescent devices.
14

Morphology-preserving chemical conversion of bioorganic and inorganic templates

Vernon, Jonathan P. 17 January 2012 (has links)
The generation of nanostructured assemblies with complex (three-dimensional, 3D) self-assembled morphologies and with complex (multicomponent) tailorable inorganic compositions is of considerable technological and scientific interest. This research demonstrates self-assembled 3D organic templates of biogenic origin can be converted into replicas comprised of numerous other functional nanocrystalline inorganic materials. Nature provides a spectacular variety of biologically-assembled 3D organic structures with intricate, hierarchical (macro-to-micro-to-nanoscale) morphologies. Morphology-preserving chemical conversion of such readily available, structurally complex templates will provide a framework for chemical conversion of synthetic organic templates and, potentially, production of organic/inorganic composites. Four research thrusts are detailed in this dissertation. First, chemical conversion of a nanostructured bioorganic template into a multicomponent oxide compound (tetragonal BaTiO₃ via layer-by-layer surface sol-gel coating and subsequent morphology-preserving microwave hydrothermal processing was demonstrated. Second, photoluminescence was imparted to bioorganic template structures through morphology-preserving chemical conversion to exhibit both the dramatic change in properties such processing can provide, and the potential utility of chemically transformed templates in anti-counterfeiting / authentication applications. Third, the reaction mechanism(s) for morphology-preserving microwave hydrothermal conversion of TiO₂ to BaTiO₃, were studied with the aid of Au inert markers on single crystal rutile TiO₂. Finally, constructive coating techniques (SSG) and moderate temperature (< 500C) heat treatments were utilized to modify and replicate structural color and were coupled with deconstructive focused ion beam microsurgery to prepare samples for microscale structure/property interrogation. Specifically, the effects of coating thickness and coating composition on reflection spectra of structurally colored templates were examined. Also, the effects of the replacement of natural material with higher index of refraction inorganic materials on optical properties were studied. The three processing research thrusts constituting chapters 1, 2 and 4 take advantage of moderate temperature processing to ensure nanocrystalline materials, either for shape preservation or to prevent scattering in optical applications. The research thrust presented in chapter 3 examines hydrothermal conversion of TiO₂ to BaTiO₃, not only to identify the reaction mechanism(s) involved in hydrothermal conversion under morphology-preserving conditions, but also to introduce inert marker experiments to the field of microwave hydrothermal processing.
15

Poly(norbornene) supported side-chain coordination complexes: an efficient route to functionalized polymers

Carlise, Joseph Raymond 11 April 2006 (has links)
This thesis begins with a brief overview of current strategies used in the synthesis of side-chain functionalizad polymers and materials. The discussion then focuses more explicitly on transition metal-based motifs and methodologies that are employed in polymer functionalization and continues with a more detailed overview of this field. The primary hypothesis that is addressed herein is that combining the versatility and strength of metal-ligand interactions with the efficiency and functional group tolerance of ROMP comprises a useful method of generating a variety of functionalized polymers and materials via side-chain metal coordination. Thus, the goal is to test this hypothesis by synthesizing functionalized polymers with a range of useful properties to demonstrate the relevance and importance of this methodology, by employing several different strategies to show the synthetic ease by which the materials can be realized. The strategies and methods discussed in the synthesis of side-chain functionalized polymers are divided into three subgroups: (1) pre-polymerization functionalization, in which all of the modifications take place on the monomer with polymerization as the last step, (2) post-polymerization functionalization, in which the polymer itself is subsequently modified, and (3) combinations of the first two strategies. It is shown that useful functional polymers and materials can be synthesized by any of the above strategies, and representative examples of each are given in both the introduction and in the body of work presented. Modes of functionalization are all based on transition metal coordination, and polymerizations are primarily carried out via ROMP. Metal coordination is shown to be a useful technique for functionalizing polymers, to creating supported emissive complexes, to modulating solution viscosity. Finally, conclusions are drawn regarding the various strategies presented herein, and potential future directions are discussed.
16

Cyclic voltammetry as a sensitive method for in situ probing of chemical transformations in quantum dots

Osipovich, Nikolai P., Poznyak, Sergei K., Lesnyak, Vladimir, Gaponik, Nikolai 13 January 2020 (has links)
The application of electrochemical methods for the characterization of colloidal quantum dots (QDs) attracts considerable attention as these methods may allow for monitoring of some crucial parameters, such as energetic levels of conduction and valence bands as well as surface traps and ligands under real conditions of colloidal solution. In the present work we extend the applications of cyclic voltammetry (CV) to in situ monitoring of degradation processes of water-soluble CdTe QDs. This degradation occurs under lowering of pH to the values around 5, i.e. under conditions relevant to bioimaging applications of these QDs, and is accompanied by pronounced changes of their photoluminescence. Observed correlations between characteristic features of CV diagrams and the fluorescence spectra allowed us to propose mechanisms responsible for evolution of the photoluminescence properties as well as degradation pathway of CdTe QDs at low pH.
17

Análisis de la Durabilidad de la Señalización Vial Horizontal Atendiendo a su Composición y Posicionamiento en la Calzada de Carreteras Secundarias en Climas Semiáridos Cálidos

Coves-Campos, Andrés 12 September 2019 (has links)
Las marcas viales constituyen la única guía óptica que en muchas ocasiones tienen los usuarios de la vía, su correcta aplicación y conservación nos puede llegar a determinar la gravedad de un accidente hasta el punto de poder llegar a evitarlo. Por tanto, el correcto mantenimiento y repintado de la señalización vial horizontal en las carreteras convencionales a nivel mundial y de la red viaria española en particular, la investigación en nuevas combinaciones de materiales y el estudio de su durabilidad dependiendo del posicionamiento que ocupa la marca vial en carretera, nos aportan, sin duda, un apoyo útil para progresar en la lucha contra la accidentalidad vial. Por ese motivo, se ha investigado, no sólo la evolución temporal de las características fundamentales de la señalización vial horizontal como son: la visibilidad diurna, la visibilidad nocturna y la resistencia al deslizamiento de nuevas combinaciones de materiales de post-mezclado y materiales base, como es la pintura fosforescente; sino que, al mismo tiempo, se ha elaborado una relación y un estudio de la vida útil de la marca vial atendiendo a sus características fundamentales según la zona de la calzada que ocupa esa marca vial, estableciendo las pautas de comportamiento de las mismas y cuándo reemplazarlas por no cumplir con los criterios mínimos de aceptación, relacionando la sección de desgaste a cada una de las marcas viales que podemos encontrar en las carreteras convencionales de la red viaria española. Para ello, hemos elaborado un testing ground (TG1), en la carretera CV-904, con un total de 36 samples, teniendo para cada sentido de circulación 18 combinaciones de materiales atendiendo a material base y material de post-mezclado (microesferas de vidrio, cargas antideslizantes no transparentes y grano de vidrio transparente), y a su sistema de aplicación (monolayer o bilayer). Además, hemos ejecutado un segundo testing ground (TG2), en la ronda interna de la propia Universidad de Alicante, donde, partiendo de los conocimientos obtenidos en el primer estudio, se han fabricado nuevas combinaciones de materiales incluyendo el material base, diferentes tipos de microesferas de vidrio y cargas antideslizantes como parte del material de post-mezclado, se ha añadido pintura con pigmentos fosforescentes para mejorar la visibilidad nocturna y barniz de recubrimiento premezclado con agregados antideslizantes para prolongar la vida útil de la marca vial, fabricando un total de 40 samples analizadas en laboratorio. No sólo se han estudiado los resultados de los parámetros fundamentales de cada sample, sino que nos hemos apoyado en la toma de fotografías in situ analizándolas cualitativamente, lo que nos ha ayudado a comprender su evolución y los resultados. Al mismo tiempo hemos tomado muestras de todas ellas para su observación en laboratorio. Tras la comparativa entre la evolución de cada característica principal de las probetas y su análisis, hemos establecido los períodos de la vida útil de cada una de ellas según la zona de afección en la que están ubicadas atendiendo a la Norma 8.2-IC. Cabe destacar que se ha dejado la línea de investigación relacionada con la interconexión entre el vehículo autónomo, la infraestructura viaria y la señalización vial horizontal abierta como principal futura línea de investigación.
18

Synthesis, characterization, and photophysics of symmetric and unsymmetric -NHC pincer platinum halide complexes and derivatives

Zhang, Min 14 December 2018 (has links)
A series of 24 new photoluminescent symmetric and unsymmetric -NHC pincer Pt complexes was synthesized and characterized, including collection of their 195Pt NMR chemical shifts. In total 18 new X-ray crystal structures, and photophysical studies of these photoluminescent -NHC pincer Pt complexes are reported. -NHC pincer Pt complexes were synthesized and characterized using new -NHC pincer based proligands [(RChetChetCRH3)X2, X = Cl, Br, or BPh4, where het represents imidazolyl, benzimidazolyl, and 1,2,4-triazolyl moieties; R = n-butyl, 3,3-dimethylbutyl, n-hexyl] as starting materials. A new method to synthesize Pt-Cl complexes to prevent halogen mixing was developed using tetraphenylborate salts as proligands. -NHC pincer complexes Pt(II) were oxidized to Pt(IV) complexes by reaction with Br2, I2, or iodobenzene dichloride. Photophysical studies showed emission of blue to red-orange color range for the Pt(II) complexes when irradiated with long wavelength UV light (360 nm). No visible emission for Pt(IV) complexes was observed upon irradiation at 360 nm. The tunable photoluminescence of the synthesized -NHC pincer Pt(II) complexes can be used as the materials for OLEDs. Parameters and scales that provide understanding of steric and electronic effects are essential to predicting properties, and, therefore, to systematically designing new ligands. Meridional tridentate pincer ligands are neither conveniently nor accurately described by existing options. A scale has been developed based on 195Pt NMR chemical shift that is reflective of the total donor ability of a multi-dentate ligand in a square planar complex and that does not suffer from cis/trans stereochemical issues. This scale, Platinum Electronic Parameter (PtEP) and defined as PtEP = -(195Pt NMR shift) in CDCl3 revealed significant deviations of -NHC pincer ligands, PCP and POCOP donor abilities from predicted extrapolations using existing TEP parameters. This initial data set demonstrates the applicability and broad potential of the PtEP scale.
19

Détection de traces d’éléments lanthanides par fluorescence en temps résolu : application industrielle au marquage anti contrefaçon et à l'analyse chimique / Detection of lanthanide elements by time-resolved fluorescence analysis : industrial application to anti-counterfeiting marking and chemical analysis

Marais, Arthur 06 February 2018 (has links)
La fluorescence en temps résolu est une méthode d'analyse spectrophotométrique avancée permettant la sélection des photons émis par luminescence sur un critère temporel. Il est ainsi possible, et cela même dans des milieux complexes et pollués issu de l'industrie, de faire émerger sélectivement le signal d'espèces luminescentes présentant des durées de vie de luminescence relativement grandes.Ce type d'analyse spectrale est particulièrement adapté à la détection de trace d'éléments lanthanides. Chacun des éléments de la série présente en effet des propriétés luminescentes uniques bien que largement fonction de la nature des ligands qui les entourent. Les travaux de thèse présentés dans ce manuscrit utilisent avantageusement la constatation précédente. Deux technologies ont étés mise sur pied et/ou optimisées pour permettre un transfert vers des domaines industriels aux cahiers des charges bien définis.Ainsi dans le domaine de la lutte anti-contrefaçon l'ajout de marqueurs luminescents à temps résolu à base de lanthanide rend possible la surveillance de l'origine et du devenir de divers produits industriels.Dans le domaine pétrolier l'analyse des effluents à l'aide de sondes luminescentes à base de lanthanide permet de quantifier le taux résiduel de plusieurs classes d'additifs chimiques et permet d'optimiser la sécurité, la rentabilité et l'impact écologique du processus d'extraction.Dernièrement un prototype de spectrofluorimètre résolu en temps adapté à un usage industriel a été mis au point pour permettre un transfert technologique du laboratoire vers le milieu industriel / Time-resolved fluorescence is an advanced spectrophotometric analysis method which allows the selection of emitted luminescent photons on a time-based parameters. It is possible to extract the signal of long-lived luminescent species even in complex and polluted matrix from the industry. This type of analysis is especially fitted for the detection of lanthanide ions. During this thesis two technologies based on time-resolved analysis were designed to answer specific industrial problematics. The first one yields the residual concentration of chemical additives used during oil and gas extraction. The second one aims at protecting crude oils and refined fuels from counterfeiting. They both rely on the use of lanthanide complex and the measurement of their luminescent properties. A prototype of time-resolved spectrofluorimeter was also built to transfer the technologies from the laboratory to the industrial world

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