The luminescence of the phosphor Sr2ZrO4 with one-dimensional chains structure

A new type of phosphor Sr2ZrO4 with one-dimensional structure was prepared by solid reaction and its luminescence is seen at room temperature. The excitation and emission spectra were measured and display broad maximum at 354 nm and 386 nm respectively. The mechanism of this luminescence is ascribed to charge transfer.

In situ UV-vis and CD thin-layer spectroelectrochemistry study of the electrochemical behavior of L-noradrenaline in alkaline solution

Electrochemical redox behavior of noradrenaline in alkaline solution on a glassy carbon electrode has been investigated by in situ UV-vis and CD spectroelectrochemistry by using a long optical path thin-layer cell. The experimental data were processed by using a double logarithmic method of analysis together with nonlinear regression which confirmed that the first step in both the oxidation of noradrenaline and reduction of noradrenochrome is a two-electron irreversible process governed by an EE mechanism. The kinetic parameters of the electrode reactions, i.e., charge transfer coefficient and the number of electrons transferred, alpha(1)n(1) = 0.11 and alpha(2)n(2) = 0.23, formal potentials modified with kinetics, E-1(0') = 0.65 (+/- 0.01) V and E-2(0') = 0.72V and standard rate cnstants, k(1)(0) = 7.0(+/-0.5)x10(-5) cm s(-1), for the first and second steps in the oxidation process of noradrenaline, and similarly, alpha(1)n(1) = 0.33, alpha(2)n(2) = 0.58, E-1(0') = 0.37(+/-0.01) V, E-0' = -0.25 (+/-0.01) V and k(1)(0) approximate to k(2)(0) = 1.06 (+/-0.05)x10(-4) cm s(-1) for the first and second steps in the reduction process of noradrenochrome were also determined.

Synthesis, luminescence, energy transfer and Langmuir-Blodgett films of amphiphilic complexes of rare earths with monooctadecyl phthalate

Three new amphiphilic rare earth complexes with only two organic long chains Ln (MOP)(2)Cl (MOP=monooctadecyl phthalate, Ln=Eu, Tb, Gd) were synthesized and characterized by elemental analysis. The complexes (Eu, Tb) showed good luminescence property with long fluorescence lifetime, whereas the intensity and lifetime of Tb complex are greater than those of Eu complex, By measuring the triplet energy levels of ligand based on energy transfer mechanism, above phenomena have been well explained. The Langmuir films of the complexes on the air/water interface were also studied and the results show that all of them have good film-forming property.

Synthesis, luminescence and intramolecular energy transfer of binary and ternary rare earth complexes with aromatic carboxylic acids and 1,10-phenanthroline

A series of binary and ternary rare earth complexes with para-substitued benzoic acids and 1,10-phenanthroline were synthesized. The phosphorescence spectra were measured and the lowest tripler state energies of ligands were determined, the phosphorescence lifetimes were obtained and intramolecular energy transfer mechanism between ligands was studied. The luminescence properties were also measured and were in agreement with the prediction. The energy match and intramolecular energy transfer process in these binary and ternary complexes were discussed in detail.

Study of cupric hexacyanoferrate-modified platinum electrodes using probe beam deflection and electrochemical quartz crystal microbalance techniques

The ion exchange mechanism accompanying the oxidation/reduction processes of cupric hexacyanoferrate-modified platinum electrodes in different aqueous electrolyte solutions has been studied by means of in situ probe beam deflection and the electrochemical quartz crystal microbalance technique. The results demonstrate that the charge neutrality of the film during the reoxidation/reduction process is accomplished predominantly by the movement of cations, but anions and/or solvent are also participator(s). Moreover, in KHC8H4O4 (potassium biphthalate) solution, the EQCM data obtained from chronoamperometry experiment are more complicated than those in KCl and K2SO4 solutions. (C) 1997 Elsevier Science Ltd.

Electron transfer between Eu and Tb in MMgF(4) systems

Emission of europium(II) and europium(III) have been observed in SrMgF4 : xEu, yTb phosphors which are synthesized in Ar or Ar/H-2 flow. The valence state of Eu is influenced by terbium. It is notable that the intensities of the ESR peaks corresponding to EU(2+) are regularly changed when terbium ion is incorporated. The typical Tb3d XPS spectrum belonging to Tb4+ is also found when Eu is codoped. This phenomena can be explained by electron transfer mechanism Eu3+ + Tb3+-->EU(2+) + Tb4+. And its equilibrium constant is studied by ESR technique.

Electron transfer between Eu3+ and Tb3+ in BaB4O7 matrix

The BaB4O7:Eu, Tb phosphors are first synthesized in air atmosphere. We investigate their luminescent properties, and find that europium(II) and europium(III) can coexist in the BaB4O7:Eu phosphor. We observed that the relative intensity of europium(II) is increased when terbium(III) is incorporated. The electron spin resonance (ESR) spectra are carried out. The intensity of ESR peaks corresponding to europium(II) is also increased when terbium(III) is increased, so the valency state of europium is influenced by terbium(III). We explain these phenomena by an electron transfer mechanism. (C) 1996 Academic Press, Inc.

Probe beam deflection study of the ion exchange between Prussian blue film or indium hexacyanoferrate film and electrolyte solutions

Probe beam deflection(PBD) technique together with electrochemical techniques such as cyclic voltammetry was used to study the ion exchange in prussian blue(PB) film and its analogue indium hexacyanoferrate (InHCF) chemically modified electrodes, The ion exchange mechanism of PB was verified as following: K2Fe2+FeI(CN)(6)(-e--K+)reversible arrow(+e-+K+)KFe(3+)Fe(I)(CN)(6)(-xe--xK+)reversible arrow(+xe-+xK+) [Fe3+FeI(CN)(6)](x)[KFe3+FeI(CN)(6)](1-x) where on reduction in contact with an acidic KCl electrolyte, H+ enter PB film before K+. Both the cations and anions participate concurrently in the redox process of InHCF, meanwhile K+ ion plays a major role in the whole charge transfer process of this film with increasing radii of anions.

ELECTRON-TRANSFER BETWEEN EU AND TB IN COMPLEX FLUORIDES

Europium (II) and europium (III) have been observed in MMgF(4):xEu, yTb (M=Ca, Sr, Ba) phosphors using their typical photoluminescence spectra when are synthesized in Ar or an Ar/H-2 stream. The valence state of Eu is influenced by terbium. It is notable that the intensities of the electron spin resonance peaks corresponding to Eu2+ change in a regular way when terbium ions are incorporated which can be explained by an electron transfer mechanism.

Electron transfer between Eu3+ and Ce3+ in SrM-F-4 matrix

Emissions of europium (II) and europium (III) have been observed in SrMgF4:Eu and SrMgF4:Eu,Ce phosphors which are synthesized in Ar flow, It is notable that the intensity of the ESR peaks corresponding to Eu2+ is increased when cerium ion is incorporated which can be explained by electron transfer mechanism.

Electron Transfer and its Equilibrium between Eu and Tb in SrMgF4 System

Emission of europium(II) and europium(III) have been observed in SrMgF4 xEu, yTb phosphors winch are synthesized in Ar flow. The valence state of En is influenced by terbium, It is noted that the intensities of the ESR peaks corresponding to Eu2+ are increased when terbium ion is codopech this can be explained by electron transfer mechanism which is Eu3++Tb3+-->Eu2++Tb4+. And its equilibrium constant is calculated.

CYCLIC VOLTAMMETRIC STUDY OF QUININE DERIVATIVES TRANSFER ACROSS THE WATER NITROBENZENE INTERFACE

Quinine derivatives, quinine hydrochloride and 8-hydroxyquinoline, transfer across the water/nitrobenzene interface was studied by cyclic voltammetry. The effect of solution acidity on the transfer behaviour was observed. Transfer mechanism was discussed

IMPEDANCE STUDY OF THE INTERFACES BETWEEN LITHIUM, POLYANILINE, LITHIUM-DOPED MNO2 AND MODIFIED POLY(ETHYLENE OXIDE) ELECTROLYTE

Impedance study was carried out for the interfaces between lithium, polyaniline (PAn), lithium-doped MnO2 and modified poly(ethylene oxide) (PEO) electrolyte under various' conditions. The interfacial charge-transfer resistances R(ct) on PEO/PAn, R(ct) on PEO/LiMn2O4 increase with depth-of-discharge and decrease after the charge of the cell containing modified PEO as electrolyte. The charge-transfer resistance R(ct) on PEO/PAn is higher than R(ct) on PEO/LiMn2O4 under the same condition, since inserted species and mechanism are different for both cases. In the case of PAn, an additional charge-transfer resistance might be related to the electronic conductivity change in discharge/charge potential range, as it was evident from a voltammetry curve. With increasing cycle numbers, the charge-transfer resistance increases gradually. The impedance results also have shown that at low frequency the diffusion control is dominant in the process of the charge and discharge of Li/PEO/PAn or Li/PEO/LiMn2O4 cell. The diffusion coefficients have been calculated from impedance data.

ANESTHETIC LIDOCAINE AND DICAINE TRANSFER ACROSS LIQUID LIQUID INTERFACES

Lidocaine transfer across the water/1,2-dichloroethane and the water/nitrobenzene interfaces has been investigated by chronopotentiometry with linear current scanning and cyclic voltammetry. The irreversible hydrolysis occurring in the phase transfer of dicaine at the water/nitrobenzene interface is discussed.

HE PHASE TRANSFER OF CO(II) CATALYZED BY 2,2 '-BIPYRIDINE AT THE WATER/NITROBENZENE INTERFACE

The chemical reactions coupled with the phase transfer of Co(Ⅱ) catalyzed by 2,2′ -bipyridine across the water/nitrobenzene interface have been observed by using cyclic voltammetry (CV). Coupled chemical reactions both in the organic phase or in the aqueus phase influence the CV behavior of successive complex phase transfer obviously and an irreversible phenomenon similar to that existed at the metal electrode/electrolyte solution interface was observed. For different complexes, the phase transfer mechanism...