Calculation of electrostatic energy H-e(fd) on 4f(N-1)5d configurations for heavy lanthanide ions

For the 4f(N-1)5d configuration the Coulomb interaction between f and d electrons was parameterized by F-k(fd) with K = 2, 4, and G(K)(fd) with K = 1, 3, 5. The spin-orbit interaction for 4f and 5d electrons can be parameterized by xi (f) and xi (d) respectively, which can be compounded into one lambda : lambda = axi (f) + bxi (d), where a and b are the corresponding coefficients. The energy expressions of H-e(fd) of the chief low-energy levels of 4f(N-) (1)5d configuration for heavy lanthanide ions were calculated and the corresponding spin-orbit parameters lambda were also given in LS coupling, which are profitable in analyzing the spectra of the heavy lanthanide ions.

Solvent extraction of scandium(III), yttrium(III), lanthanides(III), and divalent metal ions with sec-nonylphenoxy acetic acid

Such physicochemical properties of sec-nonylphenoxy acetic acid (CA-100) as the solubility in water, acid dissociation constant in water, dimerization constant in heptane, and distribution constant in organic solvent-water were measured by two-phase titration. The extraction behaviors of scandium (III), yttrium (III), lanthanides (III), and divalent metal ions from hydrochloric acid solutions with CA-100 in heptane have been investigated, and the possibilities of separating scandium (yttrium) from lanthanides and divalent metal ions have been carefully discussed. The stoichiometries of the extracted metal complexes were investigated by the slope-analysis technique. The effect of the nature of diluent on the extraction of yttrium (III) with CA100 has been studied and correlated with the dielectric constant.

Synthesis and characterization of novel lanthanocene complexes with dichalcogenolate o-carboranyl ligands

Reactions of [ Cp(2)Ln(mu-Cl)](2) (Cp = eta(5)-C5H5, Ln = Nd, Yb, Dy, Gd, Er) with an equivalent of [ (THF)(3)LiE2C2B10H10Li. (TT-IF) (THF)](2) (E = S, Se) in THF afforded the dinuclear sandwich complexes of formula[Cp(2)LnE(2)C(2)B(10)H(10)](2)[Li(THF)(4)](2) [E = S, Ln = Nd (1a), Yb (2a), Dy (3a), Gd (4a), Er (5a); E = Se, Ln = Nd (1b), Yb (2b), Dy (3b), Gd (4b), Er (5b)]. The molecular structures of complexes la, 2a and 2b were determined by the single crystal X-ray structure analyses. Two lanthanide atoms are connected by a pair chalcogen (eta(1), eta(2)-E2C2B10H10) bridging ligands and the central Ln(2)E(2) four membered ring is not planar.

Preparation of divalent rare earth ions in air by aliovalent substitution and spectroscopic properties of Ln(2+)

When alkaline earth ions in borates, phosphates or borophosphates [SrB4O7, SrB6O10, BaB8O13, MBPO5 (M=Ca,Sr)] are substituted partially and aliovalently by trivalent rare earth ions such as Sm3+, Eu3+, these rare earth ions can be reduced to divalent state by the produced negative charge vacancy V-M". The matrices must have appropriate structure containing a rigid three-dimensional network of tetragonal AO(4) groups (A=B,P). These groups can surround and isolate the produced divalent RE2+ ions from the reaction with oxygen. Therefore, this reduction reaction can be carried out even in air at high temperature. The produced divalent rare earth ions can be detected by luminescence and XANES methods and their spectroscopic properties are discussed.

Luminescence properties of transparent hybrid thin film covalently linked with lanthanide complexes

Novel hybrid thin films covalently doped with Eu3+ (Tb3+) have been prepared via direct routes involving co-condensation of tetraethoxysilane and phen-Si in the presence of Eu3+ (Tb3+) by spin-casting and their luminescence properties have been investigated in detail. Lanthanide ions can be sensitized by anchored phenanthroline in hybrid thin films. Excitation at the ligand absorption wavelength (272 nm) resulted in the strong emission of the lanthanide ions i.e. Eu3+ D-5(0)-F-7(J) (J=0, 1, 2, 3, 4) emission lines and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) due to the energy transfer from the ligands to the lanthanide ions.

Study on highly ordered luminescent Langmuir-Blodgett films of heteropolytung state complexes containing lanthanide

Luminescent thin films of heteropolytungstate complexes containing lanthanide (europium or samarium) were successfully fabricated by the Langmuir-Blodgett (LB) technique. The pressure-area isotherm of the monolayer of dimethyldioctadecylammonium. bromide (DODA) is modified rather markedly when the subphase contains the complex of Na9EuW10O36 or Na9SmW10O36. The above results indicate that the monolayer of DODA has a strong interaction with the polyanions of EuW10O369-. (or SmW10O369-). X-ray photoelectron spectra and fluorescent spectra verify that europium and tungsten atoms are 36 36 incorporated into the LB films. Ultraviolet (UV), fluorescent spectra and low-angle X-ray diffraction experiments demonstrate that these LB films have a well-defined lamellar structure. The LB film containing EuW10O369- can give off strong fluorescence 16 on UV irradiation. The characteristic emission behaviors of europium ions in LB films and in the powder of Na9EuW10O369- are discussed. It is found that the intensity ratio of the D-5(0)-F-7(2) transition to the D-5(0)-->F-7(1) transition in LB film is quite different from that in the powder of Na9EuW10O36. The difference of the ratio indicates that the site symmetry of europiurn is distorted in LB film, which is probably due to the strong electrostatic interactions between DODA and polyanions.

Syntheses and crystal structures of bis(tetrahydrofurfurylindenyl) lanthanocene chlorides (C4H7OCH2C9H6)(2)LnCl (Ln = Nd, Sm, Dy, Ho, Er, Yb)

Reaction of anhydrous lanthanide trichlorides with tetrahydrofurfuryl indenyl lithium in THF afforded bis(tetrahydrofurfurylindenyl) lanthanocene chlorides complexes (C4H7OCH2C9H6)(2) LnCl, Ln = Nd (1), Sm (2), Dy (3), Ho (4), Er (5), Yb (6). The X-ray crystallographic structures of all the six complexes were determined and these indicate that they are unsolvated nine-coordinate monomeric complexes with a trans arrangement of both the sidearm and indenyl rings in the solid state. They belong to the same crystal system (orthorhombic) and space group (P2(1)2(1)2(1)) with the same structure. Especially, they are more stable to air and moisture than the corresponding unsubstituted indenyl lanthanide complexes.

VUV-UV photoluminescence spectra of strontium orthophosphate doped with rare earth ions

The measurements of VUV-UV photoluminescence emission (PL) and photoluminescence excitation (PLE) spectra of rare earth ions activated strontium orthophosphate [Sr-3(PO4)(2):RE, RE = Ce, Sm, Eu, Tb] are performed. Whenever the samples are excited by VUV or UV light, the typical emission of Ce-3+,Ce- Sm3+, Eu3+, Eu2+ and Tb3+ ions can be observed in PL spectra, respectively. The charge transfer bands (CTBs) of Sm3+ and Eu3+ are found, respectively, peaking at 206 and 230nm. The absorption bands peaking in the region of 150-160 nm are assigned to the host lattice sensitization bands, i.e., the band-to-band transitions of PO43- grouping in Sr-3(PO4)(2). It is speculated that the first f-d transitions of Sm3+ (Eu3+), and the CTB of Tb3+ are, respectively, located around 165 (14 3) and 167 urn by means of VUV-UV PLE spectra and relational empirical formula, these f-d transitions or CT bands are included in the bands with the maxima at 150-160 nm, respectively. The valence change of europium from trivalent to divalent in strontium orthophosphate prepared in air is observe by VUV-UV PL and PLE spectra.

Preparation and luminescence properties of hybrid materials containing europium(III) complexes covalently bonded to a silica matrix

A new kind of luminescent organic-inorganic hybrid material (denoted Hybrid I) consisting of europium 1,10-phenanthroline complexes covalently attached to a silica-based network was prepared by a sol-gel process. 1,10-Phenanthroline grafted to 3-(triethoxysilyl)propyl isocyanate was used as one of the precursors for the preparation of an organic-inorganic hybrid materials. For comparison purposes, the hybrid material (denoted Hybrid II) in which phenanthroline was not grafted onto the silica backbone of the frameworks was also prepared. Elemental analysis; NMR, FT-IR, UV/vis absorption, and luminescence spectroscopies, and luminescence decay analysis were used to characterize the obtained hybrid materials. It is shown that the homogeneity of Hybrid I is superior to that of Hybrid II, and a higher concentration europium can be incorporated into Hybrid I than Hybrid II. Excitation at the ligand absorption wavelength (283 nm) resulted in the strong emission of the Eu3+ D-5(0)-F-7(J) (J = 0-4) transition lines as a result of the efficient energy transfer from the ligands to the EU3+ in Hybrid I. The number of water molecules coordinated to the europium ion was estimated, and the structure of the as-synthesized Hybrid I was predicted on the basis of the experimental results.

Environmental electroanalytical chemistry

This paper mainly reviewed the background, application and development on environmental electroanalytical chemistry, 79 literatures were cited.

XAFS at Eu-L-3 edge and UV-VUV excited luminescence of europium doped strontium borophosphate prepared in air

The local structure and the valences of europium in SrBPO5:Eu prepared in air were checked by means of XAFS at Eu-L-3 edge. From the EXAFS results, it was discovered that the doped europium atoms were nine-coordinated by oxygen atoms and the distances of bond Eu-O were 2.42 Angstrom in the host. From the XANES data, it was found that the divalent and trivalent europium coexisted in the matrix. The emission spectra excited by VUV or UV exhibited a prominent broad band due to the 4f(6)5d-4f(7) transition of Eu2+ ions, which indicated that the trivalent europium ions were reduced in air in the matrix at high temperature by the defects [V-Sr]" formed by aliovalent substitution between Sr2+ and Eu3+ ions. The VUV excitation spectra in 100-200 nm range showed that the matrix had absorption bands with the maxima at about 130 and 150 nm, respectively.

Covalent grafting of luminescent rare earth complex onto MCM-41 by postsynthesis

New luminescent hybrid mesoporous material was prepared by covalent anchoring rare earth complex onto MCM-41 by a postsynthesis approach. The monomer (referred to here as PABI) which plays double roles, i.e., as a ligand for lanthanide ion and as an organic functional molecule to modify MCM-41 is synthesized and characterized by H-1 NMR and MS. The fluorescence spectra show clearly that the hybrid mesoporous material possesses excellent luminescence characteristics. The hybrid mesoporous material retains the structure of MCM-41 after modification.

PMo12-doped carbon ceramic composite electrode based on sol-gel chemistry and its electrocatalytic reduction of bromate

A conductive carbon ceramic composite electrode (CCE) comprised of cc-type 1:12 phosphomolybdic acid (PMo12) and carbon powder in an organically modified silicate matrix was fabricated using a sol-gel method and characterized by scanning electron microscopy, cyclic voltammetry, and Osteryoung square-wave voltammetry. Osteryoung square-wave voltammograms of the modified electrode immersed in different acidic aqueous solutions present the dependence of current and redox potential on pH. The PMo12-doped CCE shows more reversible reaction kinetics, good stability and reproducibility, especially the renewal repeatability by simple polishing in the event of surface fouling or dopant leaching. Moreover, the modified electrode shows good catalytic activity for the electrochemical reduction of bromate.

In situ synthesis of terbium-benzoic acid complex in sol-gel derived silica by a two-step sol-gel method

Terbium complexes with benzoic acid and its derivatives o-hydroxybenzoic acid and p-hydroxybenzoic acid were in situ synthesized in sol-gel derived silica matrix via a two-step sol-gel process. The formation process of the complex was characterized by fluorescence spectra, absorption spectra and IR spectra. The gels that contain in situ synthesized complexes exhibit the characteristic emission bands of terbium ion. The fluorescence lifetimes of Tb3+ in the silica gels are longer than those in the pure complexes and in the solutions that contain the corresponding complexes. (C) 2000 Elsevier Science Ltd. All rights reserved.