Wyniki wyszukiwania - Biblioteka Nauki

1

Review of luminescence and magnetic properties of antiferromagnetic KMnCl3, RbMnCl3, TlMnCl3 and (CnH2n+1NH3)2MnCl4 (n = 1, 2)

100%

Pawłowska M. , Wojciechowski W.

Materials Science

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2002

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tom Vol. 20, No. 1

122-122

EN

Phenomena connected with the energy transfer in perovskite-type antiferromagnetic materials KMnCl3, RbMnCl3, TlMnCl3 and (CnH2n+1NH3)2MnCl4 (n = 1, 2) dotted with Sm3+ and Eu3+ ions, are considered and discussed in this paper. The energy transfer in the compounds studied is proved to depend upon the magnetic interactions in them.

2

Photoluminescence study of Nd3+-doped Si-rich silica films

80%

Breard D. , Gourbilleau F. , Belarouci A. , Dufour C. , Rizk R.

Optica Applicata

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2006

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tom Vol. 36, nr 2-3

187-192

EN

Nd3+-doped silicon-rich silicon oxide thin films have been fabricated by reactive magnetron co-sputtering of a pure silica target topped with Nd2O3 chips. The incorporation of silicon excess in the films has been controlled by the hydrogen partial pressure PH2 introduced in the plasma. Photoluminescence experiments have been made at room temperature using a non resonant excitation with Nd3+ ions. The influences of Nd3+ content and PH2 have been studied to improve the Nd3+ emission. Photoluminescence spectra reveal an enhancement of the Nd3+ emission at 0.9 m and 1.1 m when silicon nanoclusters and Nd3+ are embedded in a SiO2 matrix.

3

Model of energy transfer and luminescence of europium complexes

80%

Tsvirko M. , Venchikov V.

Prace Naukowe. Chemia i Ochrona Środowiska / Akademia im. Jana Długosza w Częstochowie

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2005

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tom Vol. 10

71--89

EN

The absolute quantum yield and lifetime of 5Do → 7Fj luminescence of Eu3+ ion in europium complexes with fluorinated β diketones has been measured on excitation of luminescence in the UV So → Si absorption band of the ligand in the temperature range 77-365 K. Based on the analysis of the experimental dependences obtained and solution of the balance equations for stationary and nonstationary cases, we have developed a new approach to the determination of the scheme and rate constants of actual transitions. The rate constants of all processes of electron excitation energy conversion have been determined. The role of the state with charge transfer in these processes has been revealed.

4

Optical properties of Nd:YbVO4 crystal

80%

Liu F. Q. , Sun S. Q. , Gao C. Y. , Xu J. Q.

Optica Applicata

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2015

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tom Vol. 45, nr 1

63—70

EN

Optical characteristics of a new laser crystal Nd:YbVO4 were studied. The optical parameters of a-cut and c-cut Nd:YbVO4 crystals were calculated by the Judd–Ofelt theory. The absorption crosssection of a-cut Nd:YbVO4 crystal was 5.34×10–20 cm2 at 808 nm, while it was 4.20×10–18 cm2 of c-cut Nd:YbVO4 crystal. The properties of energy transfer between Nd and Yb ions in Nd:YbVO4 crystal were discussed. In the fluorescence spectra, a peak at 472 nm appeared, which resulted from the coupling interaction between two Yb ions.

5

Luminescence based on energy transfer in xerogels doped with Tb2-xEux(WO4)3

80%

Grobelna B.

Optica Applicata

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2008

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tom Vol. 38, nr 1

39-47

EN

A series of luminescent materials consisting of Tb2-xEux (WO4)3 entrapped in silica xerogel were successfully prepared. The parameter x in the formula changed from 0.4 to 2. Spectroscopic properties such as absorption and luminescence of optically active ions were studied at room temperature. Owing to the energy transfer from the WO42- groups (ligand-metal charge transfer, (LMCT)) the lanthanide ions show their characteristic emissions in Tb2-xEux(WO4)3 entrapped in silica xerogel, i.e., 5D0 › 7FJ (J = 0, 1, 2, 3, 4) transition for Eu3+ ion and 5D4 › 7FJ (J = 6, 5, 4, 3) transition for Tb3+ ion. The energy transfer is effective for the mixed tungstate salt Tb1.35Eu0.65(WO4)3 entrapped in silica xerogel. The Eu(III) emission intensity in the materials under study increases with an increase in the annealing temperature from 600 to 900 °C. This is due to the removal of the effective O -H quenchers from the coordination sphere of the Eu(III) ion.

6

Energy transfer from Cr3+ to Nd3+ and NIR luminescence of Nd3+ in lead borate glasses

80%

Pisarska J.

Optica Applicata

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2008

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tom Vol. 38, nr 1

203-210

EN

Energy transfer processes from Cr3+ to Nd3+ and NIR luminescence of Nd3+ ions at 1.06 žm in Cr-Nd co-doped lead borate glasses have been investigated. The spectroscopic investigation indicates that Cr3+ ions are located at strong-field and weak-field sites. Replacing PbO by PbF2 in lead borate glasses slightly influences the energy transfer processes between Cr3+ and Nd3+ and NIR luminescence of Nd3+ ions. The energy transfer process occurs in both oxide and oxyfluoride glass systems, which may be due to the thermally induced population of the 4T2 excited state of Cr3+ ions and the participation of lattice phonons.

7

Elektrogenerowana chemiluminescencja kompleksów lantanowców (III) na elektrodzie Al/Al_20_3

80%

Staninski K. , Lis S.

Wiadomości Chemiczne

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2007

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tom [Z] 61, 3-4

279-296

EN

The aim of this review is to evaluate the electrochemiluminescence (ECL), both, as a method of light emission in certain types of lanthanide complexes by generating species capable of forming excited states, and for its potential use in analytical applications. The electrogenerated ECL in aqueous electrolyte solutions containing organic compounds having structural fragments such as carbonyl groups and conjugated double bonds and an oxide covered aluminum electrode doped with Ln(III) is reported. This specific electrogenerated luminescence can be achieved by producing highly oxidizing and reducing species as: hydrated electrons, hydroxyl and sulfate radicals. Such strong reactants efficiently excite the complexed lanthanide(III) ions [mainly Tb(III) and Dy(III)] by ligand to metal energy transfer, LMET. The experimental setup for ECL measurements (constructed in the Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University) is introduced. The ECL generated with aluminium electrodes having chelated lanthanide(III) complexes-doped in their thin oxide coatings is studied following cathodic pulse polarization. The ECL mechanisms induced by hot-electrons leading to the production of light at or near the electrode surface by generating species capable of forming excited states of organic ligands are described.

8

Chaotic vibration of an autoparametrical system with a non-ideal source of power

80%

Sado D. , Kot M.

Journal of Theoretical and Applied Mechanics

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2007

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tom Vol. 45 nr 1

119-131

EN

This paper studies the dynamical coupling between energy sources and the response of a two degrees of freedom autoparametrical system, when the excitation comes from an electric motor (with unbalanced mass mo), which works with limited power supply. The investigated system consists of a pendulum of the length l and mass m, and a body of mass M suspended on a flexible element. In this case, the excitation has to be expressed by an equation describing how the energy source supplies the energy to the system. The non- ideal source of power adds one degree of freedom, which makes the system have three degrees of freedom. The system has been searched for known characteristics of the energy source (DC motor). The equations of motion have been solved numerically. The influence of motor speed on the phenomenon of energy transfer has been studied. Near the internal and external resonance region, except for different kinds of periodic vibration, chaotic vibration has been observed. For characterizing an irregular chaotic response, bifurcation diagrams and time histories, power spectral densities, Poincare maps and maximaI exponents of Lyapunov have been developed.

PL

W pracy uwzględniono wzajemne oddziaływania autoparametrycznego układu drgającego o dwóch stopniach swobody i układu wymuszającego, którym jest silnik elektryczny z niewyważoną masą o znanej charakterystyce. Układ podstawowy składa się z wahadła o długości l i masie m podwieszonego do ciała o masie M zawieszcnego na elemencie sprężystym. Uwzględniając nieidealne źródło energii dodaje się do badanego układu dodatkowy stopień swobody, bada się więc układ o trzech stopniach swobody, ale czas nie występuje w równaniach w postaci jawnej. Równania ruchu rozwiązywano numerycznie i badano drgania w pobliżu rezonansu wewnętrznego i rezonansu zewnętrznego. W tym zakresie parametrów oprócz różnego rodzaju drgań regularnych mogą wystąpić również drgania chaotyczne. Charakter drgań nieregularnych weryfikowano analizując diagramy bifurkacyjne, przebiegi czasowe, transformaty Fouriera, mapy Poincare oraz maksymalne wykładniki Lapunowa.

9

Excitability of high-energy ultraviolet radiation for Dy3+ in antimony phosphate glasses

80%

Zhu C. , Zhang J. , Wang Z. , Lin H.

Materials Science Poland

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2017

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tom Vol. 35, No. 2

346--354

EN

Dy3+ doped antimony phosphate (ZASP) glasses are synthesized and the specificity of the luminescence behavior is demonstrated. Different from the conventional long-wave ultraviolet (UVA) exciting cases, the excitable area of Dy3+ doped ZASP glasses is extended to high-energy ultraviolet radiation including medium-wave ultraviolet (UVB) and short-wave ultraviolet (UVC) spectral regions. The quantum efficiency for 4F9/2 level of Dy3+ in low- and medium-concentration Dy2O3 doping cases reaches 95.0 % and 66.7 %, respectively, confirming the emission effectiveness from Dy3+ in ZASP glasses. The values of energy-transfer probability (P) have obvious difference while using 340 nm and 540 nm as monitoring wavelengths, so asthe energy-transfer efficiencies (η), which are related to the energy-transfer processes from discrepant Sb3+ donors to Dy3+ acceptors, were in-equivalent. The effective excitability of high-energy ultraviolet radiation illustrates that Dy3+ doped ZASP glasses are a promising candidate in developing visible light sources, display devices and tunable visible lasers.

10

Up-conversion fluorescence dynamics in Er3+/Yb3+ co-doped tellurite glasses

80%

Cherif A. , Kanoun A. , Maaref H.

Optica Applicata

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2011

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tom Vol. 41, nr 1

235--245

EN

The infrared to visible conversion in zinc tellurite glasses (TZG), activated by Er3+ ions and sensitized by Yb3+ ions, has been investigated under 980 nm pulsed laser excitation. The up-conversion mechanism was studied by means of time-resolved luminescence spectroscopy. A model for the dynamics of frequency up-conversion in Er3+/Yb3+ co-doped TZG based on the rate equations was proposed. The dynamics of the up-converted emissions were studied to evaluate energy rates between Er3+ and the Yb3+ ions, and the rate excited state absorption (ESA) in Er3+ ions.

11

Remarks about energy transfer in an RC ladder network

80%

Mitkowski W.

International Journal of Applied Mathematics and Computer Science

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2003

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tom 13

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nr 2

193-198

EN

The problem of energy transfer in an -ladder network is considered. Using the maximum principle, an algorithm for constructing optimal control is proposed, where the cost function is the energy delivered to the network. In the case considered, optimal control exists. Numerical simulations were performed using Matlab.

12

Optical absorption and luminescence of LiTaO₃:Cr and LiTaO₃:Cr, Nd crystals

80%

Gołąb S. , Sokólska I. , Dominiak-Dzik G. , Palatnikov M. N. , Sidorov N. V. , Biryukova I. , Kalinnikov V. T. , Ryba-Romanowski W.

Opto-Electronics Review

|

1999

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tom Vol. 7, No. 2

145-147

EN

The interest in LiNbO₃ and LiTaO₃ crystals doped with transition metal or rare eartch ions is related to their potential applications as self-switching and self-frequency doubling laser materials. In the past considerable attention has been paid to LiNbO₃ crystals doped by variety of luminescent ions. In particular LiNbO₃:Cr was investigated recently by Macfarlane et al. [1]. Energy transfer between Cr³⁺ and Nd³⁺ in LiNbO₃ has been studied and discussed by Vergara et al. [2]. In this work we investigate spectroscopic properties of Cr³⁺ and Cr³⁺ - Nd³⁺ interaction in LiTaO₃ using optical absorption, luminescence and luminescence decay times at temperatures between 5 K and 300 K. Some preliminary data obtained with singly doped LiTaO₃:Cr at low activator concentration are given in our previous work [3]. Recorded spectra indicate that both the Cr³⁺ and Nd³⁺ are located in several non - equivalent sites that differ in the strength of the crystal field. Luminescence spectrum of Cr³⁺ consists of a broad band whose maximum and intensity depend on temperature. Below about 50 K an additional sharp band with four distinct components appears in the spectrum. The broad band attributed to the spin allowed ⁴T₂ - ⁴A₂ transition of Cr³⁺ ions overlaps two absorption bands of Nd³⁺ ions at about 810 nm and 890 nm making the Cr³⁺ - Nd³⁺ energy transfer process feasible. Results of measurements are discussed and compared to those obtained with LiNbO₃:Cr.

13

Enhanced luminescence of rare-earth Tb (III) obtained by mixing of Gd (III) in a fumarate complex and intra-molecular energy transfer

80%

Shah M. D. , Want B.

Materials Science Poland

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2015

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tom Vol. 33, No. 4

685--691

EN

Trivalent lanthanide ions display fascinating optical properties. Therefore, the rare-earth complexes of terbium fumarate heptahydrate and GdTb fumarate heptahydrate were grown by using a single gel diffusion technique. The crystals were characterized by different physicochemical techniques of characterization. UV-Vis and photoluminescence spectrophotometric experiments were carried out to study the optical properties of the grown crystals. Under various excitations (339 nm, 350 nm or 368 nm) the terbium fumarate complex emitted characteristic (4f-4f) green emission of Tb3+ (5D4)-7FJ J = 6, 5, 4 and 3, respectively). Luminescence spectra showed that Gd3+ ions in the mixed complex have not affected the luminescence emission peak positions, but remarkably increased the luminescent intensities of the terbium complex. The energy-transfer mechanism between the ligand and the central Tb3+ ions and from the Gd3+ to the Tb3+ was discussed.

14

Chaotic vibration of an autoparametrical system with the spherical pendulum

80%

Sado D. , Freundlich J. , Bobrowska A.

Journal of Theoretical and Applied Mechanics

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2017

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tom Vol. 55 nr 3

779--786

EN

In the paper, the dynamics of a three degree of freedom vibratory system with a spherical pendulum in the neighbourhood of internal and external resonance is considered. It has been assumed that the spherical pendulum is suspended to the main body which is then suspended to the element characterized by some elasticity and damping. The system is excited harmonically in the vertical direction. The equation of motion has been solved numerically. The influence of initial conditions on the behaviour of the spherical pendulum is investigated. In this type of the system, one mode of vibration may excite or damp another one, and for different kinds of periodic vibrations there may also appear chaotic vibrations. For characterization of an irregular chaotic response, time histories, bifurcation diagrams, power spectral densities, Poincar´e maps and the maximum Lyapunov exponents have been calculated.

15

Oscillations of an Autoparametrical Systems with the Spherical Pendulum

80%

Sado D. , Bobrowska A.

Machine Dynamics Research

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2016

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tom Vol. 40, No. 2

155--163

EN

Dynamic properties of the three degrees of freedom autoparametric system with spherical pendulum in the neighbourhood internal and external resonance are investigated. It was assumed that the spherical pendulum is suspended in the main body which is suspended by the element characterized by elasticity and damping and is excited harmonically in the vertical direction. The spherical pendulum is similar to the simple pendulum, but moves in 3-dimensional space, so the model with spherical pendulum is more similar to the real systems than the model with simply pendulum. In this paper the position of the main body is described by coordinate z and position of the pendulum is describe by the coordinate z and two angles: θ and φ in the vertical planes. This system has three degrees of freedom. Dynamic properties of the system described by three differential equations containing strongly nonlinear terms are investigated numerically. In autoparametric system one mode of vibration may excite or damp another one, and for except periodic or quasi-periodic vibrations there may also appear chaotic vibration. For characterizing an irregular chaotic response, time histories, bifurcation diagrams, power spectral densities, Poincaré maps and maximal exponents of Lyapunov have been developed.

16

Fluorescence Studies on Benzene and Benzene Aqueous Solution in Mesoporous Silica

80%

Okada T. , Yamanaka K. , Goto Y. , Inagaki S.

Polish Journal of Chemistry

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2008

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tom Vol. 82, nr 4

729-739

EN

We have measured fluorescence spectra as well as fluorescence decay curves of highly ordered mesoporous silica, SBA-15 and FSM-16 including benzene or benzene aqueous solution as a function of temperature. An efficient energy transfer from benzene excited singlet state to a defect in the wall of mesoporous silica emitted at about 300 nm was found. On the basis of the decay analysis, it was suggested strongly that many of the benzene molecules exist in the proximity to the surface of porewallowing to the strong molecular interactions between benzene and silica wall. It is noted that the defects in the silica wall seem to play an important role in understanding of the luminescence characteristics of chromophores embedded in mesopores.

17

Influence of Parameters of Two Pendulums System With an Elastic Element on Regular and Chaotic Vibrations

80%

Sado D. , Brodowska E. T.

Machine Dynamics Research

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2017

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tom Vol. 41, No. 2

85--96

EN

In this work, a system with two degrees of freedom is studied, consisting of the two coupled pendulums, connected by the element characterized by linear elasticity of rigidity and linear damping. One of the pendulums is subjected to harmonic horizontal excitation. The equations of motion within the studied system are derived as Lagrange’s equations. For small vibrations it was assumed that displacement of the spring element is horizontal only. Exemplary results of the energy transfer, for different parameter values of the system are presented. Numerically, it was indicated that near the internal and external resonance, except different kinds of periodic vibrations, chaotic vibration may also occur. For characterizing an irregular chaotic response, the Poincare maps and maximal exponents of Lyapunov have been constructed.

18

The fundamentals for the extracellular and inter-organ electromagnetic communication in the kHz range

80%

Michalak K. P.

Current Topics in Biophysics. Supplement

|

2011

|

tom 34

|

nr A: Plenary lectures

19

Energy transfer in peptides based on phthalimide derivatives of aliphatic aminoacids

80%

Yukhimenko N. , Savchenko I. , Kolendo A. , Syromyatnikov V. , Błażejowski J. , Wiczk W.

Materials Science

|

2002

|

tom Vol. 20, No. 4

77-83

EN

Model peptides containing phthalimide derivatives of aliphatic aminoacids with various number of methylene groups in side chains have been synthesized and investigated spectroscopically. The study aimed at the creation of polymers with the intramolecular triplet-triplet excitation energy transfer. In all compounds investigated, efficient triplet-triplet energy transfer is observed, resulting in the phosphorescence only from phtalimide t-electronic system in frozen solutions at 77 K.

20

Synthesis and phosphorescent properties of the copolymers of N-vinylcarbazole, methyl methacrylate and iridium complex

70%

Wang W. , Zhou M. , Liang L. , Lin M. , Ling M.

Materials Science Poland

|

2014

|

tom Vol. 32, No. 2

206--213

EN

The copolymers containing carbazole unit and iridium complexes, such as (Ir(bpy)2Cl, Ir(mbpy)2Cl and Ir(Brbpy)2Cl, were synthesized via radical copolymerization of N-vinylcarbazole, methyl methacrylate and iridium complex. The synthesized copolymers were characterized by FT-IR, UV-Vis absorption spectroscopy and photoluminescence (PL) spectroscopy, respectively. According to the results, the copolymers (Ir(Brbpy)2Cl/PVK and Ir(mbpy)2Cl/PVK) exhibit yellow phosphorescence with an emission peak at around 553 nm under UV-visible light in the solid state. The results also reveal almost complete energy transfer from the host carbazole segments to the guest Ir complex in the copolymer film when the Ir content reaches 1.0 wt.%. The synthesized copolymers are good candidates as blue or yellow phosphorescent materials for PLED applications.