S��ntese, caracteriza����o e propriedades espectrosc��picas de criptatos de lantan��deo do tipo [Ln��(bipy)2py(CO2Et) 2(3+)]

This work reports on the synthesis, characterization (infrared and hidrogen nmr spectra) and photophysical properties (luminescence spectra and emission quantum yield) of the lanthanide cryptates [Ln<FONT FACE=Symbol>��</FONT>(bipy)2py(CO2Et) 2]3+ with Ln = Eu3+, Tb3+ or Gd3+, which can be applied as efficient Light-Conversion-Molecular-Devices. From emission spectra of [Eu<FONT FACE=Symbol>��</FONT>(bipy)2py(CO2Et) 2]3+ it was possible to assign C3 symmetry to the metal ion. The spectroscopic studies show a higher emission quantum yield (q=25%) for [Tb<FONT FACE=Symbol>��</FONT>(bipy)2py(CO2Et) 2]3+ in aqueous solution, whereas the europium cryptate presents q=14%. This is justified by a more efficient energy transfer between triplet and emission levels of terbium (T->5D4).

Estudos fotoluminescentes em compostos de ��ons terras raras coordenados por um derivado carbaz��lico

[RE(czb)3(H2O)2] complexes (where RE = Eu3+, Tb3+, Gd3+; and czb = 4-(9H-carbazol-9-yl)benzoato) have been synthesized and characterized. The Gd3+ complex was used to determine the triplet state energy of the czb ligand. Photoluminescence measurements of the complexes have been carried out under UV excitation. The Tb3+ complex exhibited a strong green luminescence indicating an efficient antenna effect, whereas the Eu3+ complex showed low red luminescence and the Gd3+ complex a blue-green luminescence from the ligand. The luminescence lifetimes and quantum yields have also been measured for the evaluation of the spectroscopic behavior of the complexes.

Sistema para realiza����o de medidas de luminesc��ncia com excita����o por Raios X

In this work is presented a versatile system for X-ray excited optical luminescence (XEOL) measurements. The apparatus was assembled from a sample holder connected to an optical fiber responsibly for the acquisition of the scintillation signal. The spectrum is registered with a CCD coupled in a spectrograph provided with diffraction gratings. The system performance was analyzed by exciting GdAlO3:Eu3+ 3.0 at.% with X-rays from a diffractometer and measuring the emission spectra. The system can be used to obtain precise and reliable spectroscopic properties of samples with various conformations without the loss of the required safety when dealing with ionizing radiations.

Eletrodo de pasta de carbono em minicavidade de contato s��lido

Este trabalho descreve a prepara����o de eletrodo de pasta de carbono (EPC) em minicavidade de contato s��lido e sua avalia����o quando a pasta de carbono cont��m ou n��o part��culas sub-micorm��tricas de SiO2(Eu3+ 2%) e SiO2(Eu3+ 2%)-lisina. Nestes estudos, medidas de voltametria c��clica e imped��ncia eletroqu��mica foram realizadas em PBS (0,1 mol L-1 pH 7,4) contendo as esp��cies redox Fe(CN)6-3/-4. Os resultados de imped��ncia foram interpretados baseados na rea����o de transfer��ncia de carga envolvendo as esp��cies Fe(CN)6-3/-4 e/ou oxig��nio em frequ��ncias mais altas e, difus��o das esp��cies eletroativas e caracter��sticas da pasta de carbono a baixas frequ��ncias. EPC-minicavidade �� apropriado para eletroan��lises usando pasta de carbono modificada.

Uusi m����ritys munasarjasy��v��n diagnostiikkaan: CA125-lektiinim����ritys

Munasarjasy��p��, naisten vaarallisin gynekologinen sy��p��, aiheuttaa viidenneksi eniten sy��p��kuolemia maailmassa. Munasarjasy��p�� todetaan Suomessa noin 500 naisella vuosittain. CA125 on glykoproteiini ja yksi ainoista k��yt��ss�� olevavista hyv��ksytyist�� biomerkkiaineista munasarjasy��v��n havaitsemiseen. CA125:n pitoisuuden normaaliraaa pidet����n 0-35 U/ml. Koholla olevaa arvoa ei voi suoraan yhdist���� munasarjasy��p����n, koska CA125-pitoisuus voi kohota my��s maksasairauden, endometrioosin, munasarjakystan tai ovulaatiokierron takia. Diplomity��n tavoitteena oli kehitt���� munasarjasy��v��n varhaiseen havaitsemiseen kohdennettu diagnostiikkatesti, joka perustui CA125-glykoproteiinin muuttuneeseen glykosylaatioon ja lektiinien hy��dynt��miseen sitojamolekyylein��. Ty��ss�� k��ytettiin analyyttin�� nelj��st�� eri l��hteest�� olevaa CA125:t��. L��htein�� olivat munasarjasy��v��n OVCAR3-solulinjassa tuotettu CA125, sek�� homogeenisesta istukkan��ytteest�� maksakirroosi ja itusolukasvain potilailta eristetty CA125. Ty��ss�� verrattiin kymment�� eri kasvilektiini��, jotka olivat p����llystetty Eu3+-nanopartikkelilla. Suurin osa ty��ss�� k��ytetyist�� kasvilektiineist�� tunnistivat istukka-CA125:n. Japaninsinisade agglutiniini tunnisti munasarja CA125:n. Vehn��alkion agglutiniini tunnisti itusolukasvain- ja maksakirroosi ���CA125:n. Ristireaktion lis��ksi ongelmaksi muodostui korkea taustasignaali. CA125-lektiinim����ritys vaatii viel�� kehityst��, jotta ristireaktio ja taustasignaalitasoa saataisiin pienennetty��. Menetelm��n kliininen hy��dynnett��vyys pit���� viel�� testataan suoraa potilaiden seerumin��ytteist��. CA125-lektiinim����rityst�� voidaan mahdollisesti k��ytt���� CA125-immunom����rityksen rinnalla tutkittaessa munasarjasy��v��n mahdollisuutta. Tuolloin menetelm��n avulla voitaneen poissulkea my��s muut pahanlaatuiset tapaukset kuten itusolukasvaimet ja maksakirroosi.

Mikrofluidiikkaan perustuvien potilasl��heisten m����ritysj��rjestelmien hy��dyt ja ongelmakohdat sek�� Tyreotropiinim����rityksen optimointi ja mikrofluidiikan hallinta vieritestaukseen soveltuvalla m����ritysalustalla

Keskitettyihin laboratoriotutkimuksiin verrattuna potilaan tai n��ytteenottopaikan l��heisyydess�� teht��v�� vieritestaus on useimmiten kustannustehokkaampaa, helpompaa ja huomattavasti nopeampaa, eik�� testin suorittamiseen v��ltt��m��tt�� vaadita erityiskoulutettua henkil��kuntaa. Potilasl��heinen diagnostiikka on muokannut terveydenhoitoalaa siirt��m��ll�� p��ivitt��isi�� ja rutiininomaisia m����rityksi�� l��helle potilasta, tulosten ollessa selvill�� l��hes v��litt��m��sti. Nopea diagnostiikkaa saattaa my��s vaikuttaa jatkohoitop����t��ksen tekemiseen sairaalaolosuhteissa. Riitt��v��n herkkyyden omaavien m����ritysj��rjestelmien suunnittelu ja valmistus on kuitenkin hankalaa, lis��ksi valmistusmateriaalien ja k��ytettyjen reagenssien tasalaatuisuus ei aina ole itsest����n selv����. Laatuvirheet ovat yleisesti vaikeasti havaittavia sek�� vaikuttavat olennaisesti m����rityksen suorittamiseen ja tulokseen. Mikroskaalalla materiaalien fysikaalinen k��yt��s muuttuu, ominaisuus otettava huomioon j��rjestelmi�� suunnitellessa. Tutkielman kokeellisessa osassa optimoitiin 107 nm:n ja 92 nm:n Eu3+-ioneja sis��lt��vi�� polystyreeni-nanopartikkeleita sek�� kahta eri anti-TSH vasta-ainetta hy��dynt��v�� heterogeeninen sandwich-tyyppinen immunom����ritys uudelle m����ritysalustalle. Ty��ss�� tarkasteltiin immunom����rityksen optimaaliselle toiminnalle olennaisia asioita kuten l��mp��tilaa m����rityksen eri pisteiss��, reaktiotilavuuksia ja -aikoja, puskureiden koostumuksia ja pitoisuuksia, leima-ainem����ri��, s��ilytysolosuhteita sek�� mikrofluidiikan vaikutuksia ja toimintaa tietokoneohjatulla mekaanisella ruiskuj��rjestelm��ll��. Diagnostiikkakasetin reaktiokammion pesutekniikat sek�� pesuaineen vahvuus sek�� koostumus olivat my��s tarkasteltavina. Nanopartikkeleiden tuottama pitk��ik��inen fluoresenssi mitattiin reaktiokammion pinnalta Victor-levylukijalla. Haastetta ty��h��n toi mikrofluidiikan hallinta ja sen ominaisuudet, p����asiassa nesteliike, kuplanmuodostus sek�� reaktiokammion onnistunut pesu. M����ritys toimii teknisesti hyvin ja oikealla tavalla. M����ritysaika oli 15 minuuttia. Aivan pienimpi�� pitoisuuksia ei kuitenkaan kyetty erottamaan taustasta. TSH-m����rityksen optimointi tuotti runsaasti teknist�� perustietoa heterogeenisen immunom����rityksen toimivuudesta kasetti-ymp��rist��ss��, mik�� helpottaa muiden samalla periaatteella toimivien m����ritysten k��ytt����nottoa. M����ritysj��rjestelm���� voidaan tulevaisuudessa k��ytt���� esimerkiksi kilpirauhasen vajaa- tai liikatoiminnan havaitsemisen lis��ksi muun muassa syd��ninfarktin varhaiseen ja nopeaan toteamiseen.

Infrared Spectroscopy of Gadolinium

Measurements of the optical reflectivity of the normal incident light along c-axis [0001] have been made on a Gadolinium single crystal, for temperatures between 50 K and room temperature just above the Curie temperature of Gd, which is 293 K. And covering the spectrum range between 100 -11000 cm-I . This work is the first study of Gd in the far infrared range. In fact it fills the gap below 0.2 eV which has never been measured before. Extreme attention was paid to the fact that Gadolinium is a very reactive metal with air. Thus, the sample was mechanically polished and carefully handled during the measurement. However, temperature dependent optical measurements have been made in the same frequency range for a sample of Gd2O3. For comparison, both samples of Gd and Gd2O3 were examined by X-Ray diffraction. XRD analysis showed that the sample was pure gadolinium and the oxide layer either does not exist, or is very thin. Furthermore, this fact was supported by the absence of any of Gd2O3 features in the Gd sample reflectivity. Kramers Kronig analysis was applied to extract the optical functions from the reflectance data. The optical conductivity shows a strong temperature dependence feature in the mid-infrared. This feature disappears completely at room temperature which supports a magnetic origin.

INVESTIGATIONS ON THE SOLVENT EXTRACTION AND LUMINESCENCE OF LANTHANOIDS WITH MIXTURES OF HETEROCYCLIC ��- DIKETONE S AND VARIOUS NEUTRAL OXO-DONORS

The thesis entitled ��� Investigations on the solvent extraction and luminescence of lanthanoids with mixtures of heterocyclic ��-diketone S and various neutral oxo-donors��� embodies the results of investigations carried out on the solvent extraction of trivalent lanthanoids with various heterocyclic ��-diketones in the presence and absence of neutral oxo-donors and also on the luminescent studies of Eu3+-heterocyclic ��-diketonate complexes with Lewis bases. The primary objective of the present work is to generate the knowledge base, especially to understand the interactions of lanthanoid-heterocyclic ��-diketonates with various macrocyclic ligands such as crown ethers and neutral organophosphorus extractants , with a view to achieve better selectivity. The secondary objective of this thesis is to develop novel lanthanoid luminescent materials based on 3-phenyl-4-aroyl-5-isoxazolones and organophosphorus ligands, for use in electroluminescent devices. In the beginning it describes the need for the development of new mixed-ligand systems for the separation of lanthanoids and the development and importance of novel luminescent lanthanoid- ��-diketonate complexes for display devices. The syntheses of various para substituted derivatives of 4-aroyl-5-isoxazolones and their characterization by various spectroscopic techniques are described. It also investigate the solvent extraction behaviour of trivalent lanthanoids with 4-aroyl-5-isoxazolones in the presence and absence of various crown ethers such as 18C6, DC18C6, DB18C6 and B18C6. Elemental analysis, IR and H NMR spectral studies are used to understand the interactions of crown ethers with 4-aroyl-5-isoxazolonate complexes of lanthanoids. The synergistic extraction of trivalent lanthanoids with sterically hindered 1-phenyl-3-methyl-4-pivaloyl-5-pyrazolone in the presence of various structurally related crown ethers are studied. The syntheses, characterization and photyphysical properties of Eu3+-4-aroyl-5-isoxazolonate complexes in the presence of Lewis bases like trictylphosphine oxide or triphenylphosphine oxide were studied.

Synthesis and Photoluminescence Properties of Novel Red Phosphors for White Light Emitting Diode Applications

Several series of Eu3+ based red emitting phosphor materials were synthesized using solid state reaction route and their properties were characterized. The present studies primarily investigated the photoluminescence properties of Eu3+ in a family of closely related host structure with a general formula Ln3MO7. The results presented in the previous chapters throws light to a basic understanding of the structure, phase formation and the photoluminescence properties of these compounds and their co-relations. The variation in the Eu3+ luminescence properties with different M cations was studied in Gd3-xMO7 (M = Nb, Sb, Ta) system.More ordering in the host lattice and more uniform distribution of Eu3+ ions resulting in the increased emission properties were observed in tantalate system.Influence of various lanthanide ion (Lu, Y, Gd, La) substitutions on the Eu3+ photoluminescence properties in Ln3MO7 host structures was also studied. The difference in emission profiles with different Ln ions demonstrated the influence of long range ordering, coordination of cations and ligand polarizability in the emission probabilities, intensity and quantum efficiency of these phosphor materials. Better luminescence of almost equally competing intensities from all the 4f transitions of Eu3+ was noticed for La3TaO7 system. Photoluminescence properties were further improved in La3TaO7 : Eu3+ phosphors by the incorporation of Ba2+ ions in La3+ site. New red phosphor materials Gd2-xGaTaO7 : xEu3+ exhibiting intense red emissions under UV excitation were prepared. Optimum doping level of Eu3+ in these different host lattices were experimentally determined. Some of the prepared samples exhibited higher emission intensities than the standard Y2O3 : Eu3+ red phosphors. In the present studies, Eu3+ acts as a structural probe determining the coordination and symmetry of the atoms in the host lattice. Results from the photoluminescence studies combined with the powder XRD and Raman spectroscopy investigations helped in the determination of the correct crystal structures and phase formation of the prepared compounds. Thus the controversy regarding the space groups of these compounds could be solved to a great extent. The variation in the space groups with different cation substitutions were discussed. There was only limited understanding regarding the various influential parameters of the photoluminescence properties of phosphor materials. From the given studies, the dependence of photoluminescence properties on the crystal structure and ordering of the host lattice, site symmetries, polarizability of the ions, distortions around the activator ion, uniformity in the activator distribution, concentration of the activator ion etc. were explained. Although the presented work does not directly evidence any application, the materials developed in the studies can be used for lighting applications together with other components for LED lighting. All the prepared samples were well excitable under near UV radiation. La3TaO7 : 0.15Eu3+ phosphor with high efficiency and intense orange red emissions can be used as a potential red component for the realization of white light with better color rendering properties. Gd2GaTaO7 : Eu3+, Bi2+ red phosphors give good color purity matching to NTSC standards of red. Some of these compounds exhibited higher emission intensities than the standard Y2O3 : Eu3+ red phosphors. However thermal stability and electrical output using these compounds should be studied further before applications. Based on the studies in the closely related Ln3MO7 structures, some ideas on selecting better host lattice for improved luminescence properties could be drawn. Analyzing the CTB position and the number of emission splits, a general understanding on the doping sites can be obtained. These results could be helpful for phosphor designs in other host systems also, for enhanced emission intensity and efficiency.

Lanthanide complexes of 2-hydroxynicotinic acid: synthesis, luminescence properties and the crystal structures of [Ln(HnicO)(2)(mu-HnicO)(H2O)] center dot nH(2)O (Ln = Tb, Eu)

New lanthanide complexes of 2-hydroxynicotinic acid (H(2)nicO) [Ln(HnicO)(2)(mu-HnicO)(H2O)] (.) nH(2)O (Ln = Eu, Gd, Tb, Er, Tm) were prepared. The crystal structures of the [Tb(HnicO)(2)(g-HnicO)(H2O)] (.) 1.75H(2)O(1) and [Eu(HniCO)(2)(mu-HnicO)(H2O)] (.) 1.25H(2)O (2) complexes were determined by X-ray diffraction. The 2-hydroxynicotinate ligand coordinates through O,O-chelation to the lanthanide(III) ions as shown by X-ray diffraction and the infrared, Raman and NMR spectroscopy results. Photoluminescence measurements were performed for the Eu(III) and Tb(III) complexes. Lifetimes of 0.592 +/- 0.007 and 0.113 +/- 0.002 ms were determined for the Eu3+ and Tb3+ emitting states D-5(0) and D-5(4), respectively. A value around 30% was found for the D-5(0) quantum efficiency. The energy transfer mechanisms between the lanthanide ions and the ligands are discussed and compared with those observed in similar complexes involving the 3-hydroxypicolinate ligand based on the luminescence of the respective Gd3+-based complexes. (C) 2003 Published by Elsevier Ltd.

Lanthanide speciation in potential SANEX and GANEX actinide/ 2 lanthanide separations using Tetra-N-Donor extractants

Lanthanide(III) complexes with N-donor ex-tractants, which exhibit the potential for the separation of minor actinides from lanthanides in the management of spent nuclear fuel, have been directly synthesized and characterized in both solution and solid states. Crystal structures of the Pr3+, Eu3+, Tb3+, and Yb3+ complexes of 6,6���-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin3-yl)-1,10-phenanthroline(CyMe4-BTPhen) and the Pr3+, Eu3+, and Tb3+ complexes of 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotria-zin-3-yl)-2,2���-bypyridine (CyMe4-BTBP) were obtained. The majority of these structures displayed coordination of two ofthe tetra-N-donor ligands to each Ln3+ ion, even when in some cases the complexations were performed with equimolar amounts of lanthanide and N-donor ligand. The structures showed that generally the lighter lanthanides had their coordination spheres completed by a bidentate nitrate ion, giving a 2+ charged complex cation, whereas the structures of the heavier lanthanides displayed tricationic complex species with a single water molecule completing their coordination environments. Electronic absorption spectroscopic titrations showed formation of the 1:2 Ln3+/LN4���donor species (Ln = Pr3+, Eu3+, Tb3+) in methanol when the N-donor ligand was in excess. When the Ln3+ ion was in excess, evidence for formation of a 1:1 Ln3+/LN4���donor complex species was observed. Luminescent lifetime studies of mixtures of Eu3+ with excess CyMe4-BTBP and CyMe4-BTPhen in methanol indicated that the nitrate-coordinated species is dominant in solution. X-ray absorption spectra of Eu3+ and Tb3+ species, formed by extraction from an acidic aqueous phase into an organic solution consisting of excess N-donor extractant in pure cyclohexanone or 30% tri-n-butyl phosphate (TBP) in cyclohexanone, were obtained. The presence of TBP in the organic phase did not alter lanthanide speciation. Extended X-ray absorption fine structure data from these spectra were fitted using chemical models established by crystallography and solution spectroscopy and showed the dominant lanthanide species in the bulk organic phase was a 1:2 Ln3+/LN���donor species.

Effects of gamma radiation on the photoluminescence properties of polycarbonate matrices doped with terbium complex

Luminescent films containing terbium complex [Tb(acac)(3)(H(2)O)(3)] (acac = acetylacetonate) doped into a polycarbonate (PC) matrix were prepared and irradiated at low-dose gamma radiation with ratio of 5 and 10 kGy. The PC polymer was doped with 5% (w/w) of the Tb(3+) complex. The thermal behavior was investigated by utilization of differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). Changes in thermal stability due to the addition of doping agent into the polycarbonate matrix. Based on the emission spectra of PC:5% Tb(acac)(3) film were observed the characteristic bands arising from the (5)D(4) -> (7)F(J) transitions of Tb(3+) ion (J = 0-6), indicating the ability to obtain the luminescent films. Doped samples irradiated at low dose of gamma irradiation showed a decrease in luminescence intensity with increasing of the dose. (C) 2009 Elsevier Ltd. All rights reserved.

Rare earth centers properties and electron trapping in SnO2 thin films produced by sol-gel route

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

S��ntese, caracteriza����o e estudo fotof��sico de complexos de 4,4- diaminoestilbeno-2,2-dissulfonato com ��ons lantan��deos

This is a work involving fundamental studies of chemistry where the synthesis and structural characterization, as well as a possible future application of these new compounds as luminescent sensors or sunscreen agents, complexes with 4,4 diaminostilbene-2,2-disulfonic (DSD) and trivalent lanthanide ions La3+, Nd3+, Eu3+, Gd3+ and Yb3+, were synthesized in the ratio of 3 mmol: 1 mmol (DSD: lanthanides). The complexes obtained with these ions were present in powder form and were characterized by complexometric titration with EDTA CHN Elemental analysis, molecular absorption spectroscopy in the ultraviolet region, the absorption spectroscopy in the infrared, thermal analysis (TG / DTG), Nuclear Magnetic Resonance - NMR 1H and Luminescence Spectroscopy. The complexometric titration and CHN analysis, confirmed the TG / DTG which suggest that these complexes have the following general chemical formulas: [La2(C14H12S2O6N2)2(H2O)2Cl2].7H2O,[Nd2(C14H12S2O6N2)2(H2O)2Cl2].6H2O,[Eu2(C14 H12S2O6N2)2(H2O)2Cl2].7H2O,[Gd2(C14H12S2O6N2)2(H2O)2Cl2].4H2O e [Yb2(C14H12S2O6N2)2(H2O)2].6H2O. The disappearance of the bands in the infrared spectrum at 2921 cm-1 and 2623 cm-1 and the displacement of the bands in the spectra of the amine complex indicate that the lanthanide ion is coordinated to the oxygen atoms and the sulfonate groups of the nitrogens amines, suggesting the formation of the dimer. The disappearance of the signal and the displacement signal SO3H amines in the 1H NMR spectrum of this complex are also indicative coordination and dimer formation. The Thermogravimetry indicates that the DSD is thermally stable in the range of 40�� to 385��C and their complexes with lanthanide ions exhibit weight loss between 4 and 5 stages. The Uv-visible spectra indicated that the DSD and complexes exhibit cis isomers. The analysis of luminescence indicates that the complexes do not exhibit emission in the region of the lanthanides but an intense emission part of the binder. This is related to the triplet states of the ligand, which are in the lowest energy state emitting lanthanide ions, and also the formation of the dimer that suppress the luminescence of ion Eu3+. The formation of dimer was also confirmed by calculating the europium complex structure using the model Hamiltonian PM6 and Sparkle

Filmes de tit��nio-sil��cio preparados por spin e dip-coating

The conditions for the preparation of luminescent materials, consisting of Eu3+ ions entrapped in a titanium matrix, in the forma of a thin film, using the sol-gel process, are described. The films were obtained from sols prepared with TEOS and TEOT, in the presence of acetylacetone as the hidrolysis-retarding agent, using the dip-coating and spin-coating techniques. The influence of these techniques on the films based on titanium and silicon are presented. The Eu3+ was used as a luminescent probe. The films have been characterized by luminescence, reflection and transmittance. The thickness of the films could be related to the preparation procedure. Transparent thin films have been prepared by dip-coating technique.