bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical properties of coloured LiF crystals with given content of oxygen, hydroxyl and metal impurities
Authors: Baldacchini G. , Goncharova O. , Kalinov V. S. , Montereali R. M. , Nichelatti E. , Vincenti A. , Voitovich A. P. 
Published: March 2007

AbstractOptical absorption and emission spectra have been studied in LiF crystals containing oxygen, hydroxyl and metal impurities, and coloured with γ ‐rays at room temperature with doses up to 83 kGy. Well‐defined bands in absorption and emission spectra of uncoloured samples have been attributed to impurities. Colouring of the same crystals adds new spectroscopic features, which are related to various colour centres, but at the same time depends strongly on the impurity content, especially as far as their formation efficiency is concerned. The connection between impurities and colour centres will be discussed on the basis of optical spectra of uncoloured and coloured, and also pre‐annealed and bleached crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dependence of long‐lived defect creation on excitation density in MgO single crystals
Authors: Lushchik Aleksandr , Kärner Tiit , Lushchik Cheslav , Vasil'chenko Eugene , Dolgov Sergei , Issahanyan Vigen , Liblik Peeter 
Published: March 2007

AbstractThe processes of the creation, stabilization and annealing of anion Frenkel defects have been investigated in MgO and MgO:Be single crystals irradiated by α particles, uranium swift ions or fast neutrons at 300 K and also additionally irradiated by 5 keV electrons at 6 K. Neutral oxygen interstitials undergo stabilization due to their association with the holes localized near Be2+ ions or near cation vacancies. The peculiarities of the processes of nonimpact creation and stabilization of point defects under conditions of a high density of electronic excitations formed in the tracks of swift heavy ions have been considered by the example of MgO crystals, where the creation energy of a pair of long‐lived Frenkel defects exceeds the energy gap, EFD > Eg. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitation processes of the blue luminescence in crystalline SiO2 probed by synchrotron radiation measurements
Authors: Cannas Marco , Agnello Simonpietro , Boscaino Roberto , Gelardi Franco Mario , Trukhin Anatoly 
Published: March 2007

AbstractLuminescence properties of crystalline α‐quartz were investigated by time‐resolved spectroscopy under pulsed synchrotron radiation excitation in the vacuum ultraviolet range. Our results evidence that two emission bands overlap at 2.7 eV, both being observed only at low temperature. The first contribution is excited by band‐to‐band transition and is related to the radiative recombination of a self trapped exciton occurring in a time scale of a few ms, the second is associated with defects induced in quartz by γ‐ and β‐radiation, is excited at 7.6 eV and its lifetime is 3.6 ns at T = 10 K. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of Pb2+ ions in the luminescence of LuAG:Ce single crystalline films
Authors: Babin V. , Gorbenko V. , Makhov A. , Nikl M. , Zazubovich S. , Zorenko Y. 
Published: March 2007

AbstractSteady‐state and time‐resolved emission and excitation spectra and luminescence decay kinetics were studied at 4.2‐350 K under excitation in the 2.5‐15 eV energy range for the undoped and Ce3+‐doped Lu3Al5O12 (LuAG) single crystalline films grown by Liquid Phase Epitaxy method. The spectral bands arising from the single Pb2+‐based centers were identified. Competition between Pb2+ and Ce3+ ions in the processes of energy transfer from the LuAG crystal lattice was evidenced. Due to overlap of the 3.61 eV emission band of Pb2+ centers with the 3.6 eV absorption band of Ce3+ centers, an effective energy transfer from Pb2+ ions to Ce3+ ions occurs, resulting in the appearance of slower component in the luminescence decay kinetics of Ce3+ centers and decrease of the Ce3+‐related luminescence intensity. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decay course of slow emission component for thallium and lead centers in some alkali halide crystals
Authors: Polák K. , Mihóková E. , Schulman L. S. 
Published: March 2007

AbstractWe discuss some of our results on KCl and KBr crystals doped with very low concentration of Pb2+ and Tl+ ions. The aim is to understand validity of two theoretical models developed to explain an anomaly of some slow luminescence components. Low doping concentration follows an effort to suppress any parasitic effects on the measured decay curve. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flight to Mars and radiation defects in Li2B4O7 and KTiOPO4 crystals
Authors: Grachev V. , Malovichko G. , Pankratov V. , Rust T. , Burak Ya. 
Published: March 2007

AbstractSolar, space, laser and nuclear reactor radiations lead to the appearance of defects in complex oxides and to inevitable performance degradation of devices based on these materials. Since many radiation defects are paramagnetic ones, the electron paramagnetic resonance, EPR is one of the most suitable method for their study. Results of optical and EPR study of defects in as grown and irradiated Li2B4O7 and KTiOPO4 crystals are presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optically‐detected magnetic resonance of molecular color centers CO3– and NO3 in gamma‐irradiated beryl
Authors: Pinheiro M. V. B. , Krambrock K. , Guedes K. J. , Spaeth J.‐M. 
Published: March 2007

AbstractIn this paper we identify, with optically‐detected magnetic resonance via the magnetic circular dichroism of the absorption, the NO3 and CO3– molecular radicals trapped in the structural channels of gamma‐irradiated beryl. We confirm that, along with the CO3–, the NO3 is also responsible for the blue color by introducing several absorption peaks between 14500 cm–1 and 18000 cm–1 (720 nm down to 540 nm). Their individual contributions to the overall many‐peak optical spectra have been established and most of the transitions could be explained in terms of a combination of crystal‐field and spin‐orbit split 2A2′ → 2E′ transition plus vibronic replicas. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Intrinsic luminescence and energy transfer processes in pure and doped YVO4 crystals
Authors: Pankratov V. , Grigorjeva L. , Millers D. , Yochum H. M. 
Published: March 2007

AbstractLuminescence properties of nominally pure and neodymium doped YVO4 single crystals have been studied by means of time‐resolved luminescence spectroscopy technique. It was detected that, besides the main well‐known blue excitonic emission band near 2.8 eV, an additional UV emission band at ∼3.1 eV appears in the spectra of intrinsic luminescence at low temperatures (∼80 K) for all crystals studied. Decay time of the UV band is much faster in comparison with the blue one and the UV band is quenched at temperatures above 150 K. Origin of the UV emission band is discussed. A significant rise front was observed in the relaxation kinetics of Nd3+ emission under band‐to‐band excitation. The time constant of the rise front of the Nd3+ emission is very close to decay time of the blue emission in a wide temperature range. It is suggested that the energy transfer process from the host lattice to neodymium ions occurs via excitonic states. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Colloidal copper in soda‐lime silicate glasses characterised by optical and structural methods
Authors: Macalik B. , Krajczyk L. , Morawska‐Kowal T. 
Published: March 2007

AbstractOptical and structural characteristics of phase separated soda lime silicate glasses doped with monovalent copper have been studied for samples exchanged in molten copper chloride and afterwards thermally treated in a gaseous hydrogen atmosphere. The created colloidal particles are of different size, and their diameter increases with the penetration depth of the copper ions, which in turn depends on the chemical and thermal treatment. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of MgO ceramics irradiated in different reactors
Authors: Kvatchadze V. , Dekanozishvili G. , Kalabegishvili T. , Vylet V. , Galustashvili M. , Akhvlediani Z. , Keratishvili N. , Zardiashvili D. , Sobolevskaia S. 
Published: March 2007

AbstractHigh‐temperature thermo‐stimulated luminescence (TSL) of translucent ceramic material MgO:0.2 weight% LiF has been studied in order to determine whether it can be used to estimate the fast neutron fluences. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initio calculation of wurtzite‐type GaN nanowires
Authors: Gulans Andris , Tale Ivars 
Published: March 2007

AbstractAb initio calculations of wurtzite‐type GaN nanowires have been performed using density functional theory. Different shapes of nanowires of with similar diameters of around 2 nm have been considered to determine the stability of the structures. The quantitative similarities in the local properties obtained and dangling bond energies of nanowires and bulk surfaces have lead to a simple model model for a calculation of effective Young's modulus of nanowires of arbitrary diameters and shapes. The size dependence of the Young's modulus reveals a softening of GaN nanowires with the decrease of the diameter. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy transfer and excitation processes in thin films of rare‐earth organic complexes for NIR emission
Authors: Pietrantoni S. , Francini R. , Pizzoferrato R. , Penna S. , Paolesse R. , Mandoj F. 
Published: March 2007

AbstractWe have synthesized and studied the excitation‐emission properties of three erbium‐coordinating porphyrin‐based complexes for solid state films with emission in the 1530‐nm band. In two of these complexes the C‐H groups of the organic part (ligand) have been substituted with C‐F and/or C‐Br ones in order to assess the role of the deactivation by the vibronic levels in the strong quenching of NIR emission. Time‐resolved phosphorescence measurements have also been carried out in gadolinium analogues to verify the influence of substitution on the singlet‐triplet intersystem crossing processes. The observed increase in the NIR emission is not consistent with the complete removal of quenching and the presence of other mechanisms for deactivation should be investigated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dosimetric characterization of wollastonite‐teflon composites
Authors: Souza Divanizia N. , Melo Adeilson P. , Oliveira Maria G. , Caldas Linda V. E. 
Published: March 2007

AbstractIn this work, the thermoluminescent properties of pellets containing powdered Wollastonite embedded in Teflon were studied. The preliminary results using gamma rays from a 60Co source showed linearity at the calibration curve between 0.5 Gy and 10 Gy. The main TL peaks are located at 125, 200 and 245 °C. The repeatibility of TL response presented a maximum coefficient of variation of 6.3%. The material can be used in successive irradiation‐reading‐annealing cycles without an appreciable change in its sensitivity. The calibration curve for a gamma source (60Co) up to 20 kGy and the minimum detection limits were obtained. The results show that these Wollastonite‐Teflon pellets present possibilities for use as TL dosimeters. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of transition metal ion‐doped MgAl2O4 spinel for laser application
Authors: Jouini Anis , Yoshikawa Akira , Brenier Alain , Fukuda Tsuguo , Boulon Georges 
Published: March 2007

AbstractTi and Mn‐doped MgAl2O4 spinel have been successfully grown by the micro‐pulling‐down method and spectroscopic properties have been investigated in view of the potential use as a short‐wavelength tunable solid‐state laser. Strong blue emission is observed from Ti‐doped MgAl2O4 and green emission from a Mn‐doped one. The optimum conditions to obtain the strongest emission were studied by changing the doping concentration. These two broad emission bands around 455 nm for Ti (decay time of 5.7 µs) and 518 nm for Mn (decay time of 6.11 ms) were obtained by pumping in the UV region at 266 nm and 355 nm, respectively. Discussion is submitted to assign the origins of each type of fluorescence in spinel. Ni2+‐doped crystal exhibits a broad absorption band at around 980 nm suitable for InGaAs laser diode pumping and a broad emission band in the near infrared with two decay times at 210 µs and 850 µs respectively and high quantum yields. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
What may be expected from the “microwave resonant cavity technique” applied to rare‐earth‐doped insulating materials?
Authors: Loudyi H. , Guyot Y. , Kazanskii S. A. , Gâcon J.‐C. , Pédrini C. , Joubert M.‐F. 
Published: March 2007

AbstractThe principle of measurements using the “microwave resonant cavity technique” applied to rare‐earth‐doped insulating materials is reviewed and the physical nature of the expected signals is discussed. Experimental results concerning both single crystal and powdered samples of Lu2SiO5: Ce3+ are presented and discussed as typical examples. From measurements at various temperatures between 300 and 5 K and under different pulsed laser beam powers, it is shown that detailed information on the rare earth photoionization process, photoconductivity dynamics and trapping effects may be gained, in addition to photoconductivity spectra. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of ferroelectric nanopowders by EPR method
Authors: Slipenyuk A. M. , Kondakova I. V. , Glinchuk M. D. , Laguta V. V. 
Published: March 2007

AbstractBaTiO3 nanopowders with different particle sizes have been studied by Electron Paramagnetic Resonance method over a temperature range covering the ferroelectric‐paraelectric transition. Iron and manganese impurities were used as probes for these experiments. The evolution of the spectra over the transition was observed through 1) the change in symmetry of Fe3+ from tetragonal to cubic and 2) the appearance beyond TC of Mn2+ characteristic lines. The results were analyzed according to a theoretical model proposed by one of the authors to extract the distribution of the particles size from the electron paramagnetic resonance spectra. Both the mean particle radius R0 and the dispersion σ showed a very good agreement with the data obtained from direct measurement of the size distribution. This evidences both the critical influence of the nanoparticles sizes distribution on the EPR spectra's main features and on the temperature dependence of the polarization. In the framework of the theoretical model proposed by one of the authors the distribution of the particles size was extracted from the electron paramagnetic resonance spectra. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoluminescence study of cerium‐doped lanthanum halides
Authors: Sellès O. , Fasoli M. , Vedda A. , Martini M. , Gourier D. 
Published: March 2007

AbstractPoint defects and impurities play a major role in optical properties of scintillators, as they can be at the origin of afterglow emission, which are detrimental for the applications. Spectrally‐resolved thermally stimulated luminescence (TSL) is used here to study defects possibly affecting scintillation properties of LaCl3:Ce and LaBr3:Ce samples grown by Saint‐Gobain Crystals & Detectors. In the case of LaCl3:Ce, after X‐ray irradiation two major glow peaks with complex structures are detected at 23 K and 63 K (when measured at a heating rate of 0.1 K/s). A more composite structure of the TSL pattern of LaBr3:Ce is observed. Possible explanations and implications of these findings are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oxide and nitride protective layers on stainless steel studied by AES, WDS and XPS
Authors: Mandrino Djordje , Lamut Martin , Godec Matjaž , Torkar Matjaž , Jenko Monika 
Published: March 2007

AbstractProtective surface layers on AISI 321 stainless steel were prepared by thermal treatments at two different temperatures in air and two controlled atmospheres. Different oxide and/or nitride layers were formed. Surface morphology of the layers was investigated by scanning electron microscopy (SEM). Auger electron spectroscopy (AES) depth profiling of the samples was performed. Since depth profiling suggested layer thicknesses of the order of hundreds of nanometres, an attempt was made to obtain some fast, averaged information about the layer compositions using wavelength dispersive spectroscopy (WDS) at two different beam energies to obtain probing depths best suited to the layer thickness. X‐ray photoelectron spectroscopy (XPS) profiling of one layer was also performed to obtain information about the chemical states of the elements inside the layer. The analysed samples showed considerable differences with respect to their surface morphology, oxide/nitride layer thicknesses, compositions and layer–metal interface thickness. Copyright © 2007 John Wiley & Sons, Ltd.
Network structure and innovation: The leveraging of a dual network as a distinctive relational capability
Authors: Capaldo Antonio 
Published: March 2007

AbstractThis paper employs comparative longitudinal case study research to investigate why and how strong dyadic interfirm ties and two alternative network architectures (a ‘strong ties network’ and a ‘dual network’) impact the innovative capability of the lead firm in an alliance network. I answer these intrinsically cross‐level research questions by examining how three design‐intensive furnishings manufacturers managed their networks of joint‐design alliances with consulting industrial design firms over more than 30 years. Initially, in order to explore the sample lead firms' alliance behavior, I advance an operationalization of interorganizational tie strength. Next, I unveil the strengths of strong ties and the weaknesses of a strong ties network. Finally, I show that the ability to integrate a large periphery of heterogeneous weak ties and a core of strong ties is a distinctive lead firm's relational capability, one that provides fertile ground for leading firms in knowledge‐intensive alliance networks to gain competitive advantages whose sustainability is primarily based on the dynamic innovative capability resulting from leveraging a dual network architecture. Copyright © 2007 John Wiley & Sons, Ltd.
Three Novel Mixed‐ligand Cadmium(II) Sulfonates with Aza‐aromatic Skeltons as Co‐ligands
Authors: Yang En‐Cui , Dai Pei‐Xia , Wang Xiu‐Guang , Ding Bin , Zhao Xiao‐Jun 
Published: March 2007

AbstractTo survey the influence of aza‐aromatic co‐ligands on the structure of Cadmium(II) sulfonates, three Cd(II) complexes with mixed‐ligand, [CdII(ANS)2(phen)2] (1), [CdII(ANS)2(2,2′‐bipy)2] (2) and [CdII(ANS)2(4,4′‐bipy)2]n (3) (ANS = 2‐aminonaphthalene‐1‐sulfonate; phen = 1,10‐phenanthroline; 2,2′‐bipy = 2,2′‐bipyridine; 4,4′‐bipy = 4,4′‐bipyridine) were synthesized by hydrothermal methods and structurally characterized by elemental analyses, IR spectra, and single crystal X‐ray diffraction. Of the three complexes, ANS consistently coordinates to Cd2+ ion as a monodentate ligand. While phen in 1 and 2,2′‐bipy in 2 act as N,N‐bidentate chelating ligands, leading to the formation of a discrete mononuclear unit; 4,4′‐bipy in 3 bridges two CdII atoms in bis‐monodentate fashion to produce a 2‐D layered network, suggesting that the conjugate skeleton and the binding site of the co‐ligands have a moderate effect on molecular structure, crystal stacking pattern, and intramolecular weak interactions. In addition, the three complexes exhibit similar luminescent emissions originate from the transitions between the energy levels of sulfonate anions.
On the Interchange Ability of the N‐donor Position in the Rare Earth Coordination Polymers $^{1}_{\infty}\rm [Ln(Btz)_{3}(L)]$, L = BtzH, Ph(NH2)2, NH3, and Pyridine
Authors: Müller‐Buschbaum Klaus , Mokaddem Yassin 
Published: March 2007

AbstractBenzotriazolates of the rare earth elements form chain like coordination polymers of the formula $^{1}_{\infty}\rm [Ln(Btz)_{3}(L)]$. An additional neutral ligand L saturates the coordination spheres of the trivalent lanthanide ions and, depending on the reaction conditions, can be a varying donor (L = BtzH, Ph(NH2)2, NH3 and Py). Reactions in the BtzH (1H‐benzotriazole) melt result in coordination of benzotriazole and its thermal decomposition products as L. We have now investigated if the site occupied by L can be exchanged with other N donor ligands. Pyridine can substitute BtzH, Ph(NH2)2 and NH3 under solvothermal conditions giving the coordination polymer $^{1}_{\infty}\rm [Ln(Btz)_{3}(Py)]$ even for the biggest LnIII cation lanthanum without changing the overall strand structure. Chains proof to be the chemically favoured and stable structure fragment with the L position being the chemically variable site.
Synthesis, Structure and Raman Data of the New Binuclear Zirconium Complex [Ph4P]2[(ZrCl4Py)2O], with a Zr‐O‐Zr Bridge
Authors: Chen Hao‐Hong , Zhao Jing‐Tai , Siefert Ralf , Peppel Tim , Köckerling Martin 
Published: March 2007

AbstractThe new Zirconium(IV) coordination compound [Ph4P]2[(ZrCl4Py)2O] (Ph = phenyl, Py = pyridine) was synthesized by dissolving ZrCl4, [Ph4P]Cl and a stoichiometric amount of NaOH/Na mixture in pyridine or pyridine/organic solvent mixtures. The title phase was obtained as colourless crystals. The crystal structure of [Ph4P]2[(ZrCl4Py)2O] was determined. It crystallizes monoclinic, P21/c, Z = 4, a = 13.412(2), b = 13.461(2), c = 16.442(3) Å, β = 102.72(1)°. The structure consists of isolated tetraphenylphosphonium cations and [(ZrCl4Py)2O]2− complex anions. The centrosymmetric complex anion contains a linear Zr–O–Zr bridge. Each Zr atom is coordinated by one oxygen dianion, the N atom of one pyridine ring and four chloro ligands in a distorted octahedral geometry. The Raman spectrum of [Ph4P]2[(ZrCl4Py)2O] is also reported. Most of the observed frequencies can be assigned to vibrations of the tetraphenylphosphonium cations and the pyridine rings.
Phosphino[tris(trimethylsilyl)methyl]Boranes and 2,4‐Bis[tris(trimethylsilyl)methyl]‐1,3,2,4‐diphosphadiboretanes [1]
Authors: Jetzfellner R. , Nöth H. , Paine R. T. 
Published: March 2007

AbstractThe reaction of tris(trimethylsilyl)methylboron dihalides (Me3Si)3CBX2 (X = Cl, F) with the lithium phosphides LiPHtBu and LiPHmes leads to the phosphinoboranes (Me3Si)3CBX‐(PHR), (Me3Si)3CB(PHR)2 or the 1,3,2,4‐diphosphadiboretanes [(Me3Si)3CB(PR)]2, depending on the ratio of the reagents, the reaction temperature and concentration. High dilution and low temperatures are required for the synthesis of (Me3Si)3CB(Hal)PHR (1–3) in order to prevent the formation of (Me3Si)3CB(PHR)2 (4 and 5). The latter compounds are best prepared in a two step phosphination from (Me3Si)3CBHal2 and LiPHR. At higher temperatures the four‐membered 1,3,2,4‐diphosphadiboretanes [(Me3Si)3CB(PR)]2 6 and 7 are the most stable compounds. On the other hand, compounds of type (Me3Si)3CB(Hal)PR2, 8 and 9, are thermally more stable than the monophosphinoboranes 1–3. Phosphinoboranes of type (Me3Si)3CB(PR2)2 (R = tBu, mes) could not be prepared. NMR and mass spectral data are in accord with the monomeric nature of compounds 1 to 9.
[{Na(7‐Nitro‐5‐sulfonate‐naphthalene‐1,4‐dicarboxy‐acid (H2O)2}·H2O]n: A Water‐Soluble 2D Layer Polymeric Complex with Microporous Molecular Channels
Authors: Wu Rui‐Feng , Zhang Tong‐Lai , Qiao Xiao‐Jing , Zhang Jian‐Guo , Yang Li , Wang Shao‐Zong 
Published: March 2007

AbstractThe X‐ray crystallographic studies are reported for a water‐soluble sodium complex of organic acid, {[Na(NSNDC)(H2O)2]·H2O}n, (NSNDC = 7‐Nitro‐5‐sulfonate‐napthalene‐1,4‐dicarboxy‐acid). It contains layers of vertically oriented NNSDC‐anions sandwiching cations and water molecules. The rows of anions are linked in a direction by sodium ions and along b by hydrogen bonding, which have microporous channels (9.410 × 3.210Å2) along the crystallographic b‐axis. Considering the Na coordination environments, π‐π stacking interaction between aryl ring and hydrogen bonds, the title compound represents a stably 2D infinitely extended structure.