Search results for "physical chemistry"
showing 10 items of 1199 documents
A magnetic study of a layered lanthanide hydroxide family: Ln8(OH)20Cl4·nH2O (Ln = Tb, Ho, Er)
2018
Three layered lanthanide hydroxides (LLHs), with the general formula Ln8(OH)20Cl4·nH2O (Ln = Tb (1), Ho (2), Er (3)), were prepared and magnetically characterized. These compounds were further diluted within a yttrium diamagnetic matrix, LYH:xLn, LYH:0.044Tb (1’), LYH:0.045Ho (2’), and LYH:0.065Er (3’), being the study complemented with theoretical calculations in order to understand the electronic configuration and the contributions to the slow relaxation behavior. In the pure compounds dominant 3D ferromagnetic interactions are observed, with a small magnetization hysteresis at 1.8 K for 1, while the magnetically diluted solid solutions display slow relaxation of the magnetization at low …
Hybrid organic-inorganic mononuclear lanthanoid single ion magnets
2019
The first family of hybrid mononuclear organic-inorganic lanthanoid complexes is reported, based on [PW11O39]7− and 1,10-phenanthroline ligands. This hybrid approach causes a dramatic improvement of the relaxation time (×1000) with a decrease of the optimal field while maintaining the Ueff of the inorganic analogues.
Doped zirconia phase and luminescence dependence on the nature of charge compensation
2017
Financial support provided by the Scientific Research Project for Students and Young Researchers Nr. SJZ2015/25 carried out at the Institute of Solid State Physics of the University of Latvia is greatly acknowledged.
Mechanochemical synthesis of an Eu(III) complex. Preparation and Luminescence Properties of PMMA:[C42H38N5O19Eu] Hybrid Films
2015
Abstract Photoluminescent films of poly(methyl methacrylate), PMMA, doped with the complex [EuL2(H2O)2(NO3)3] were prepared, where L is the neutral ligand 2,6-bis[2-formylphenoxymethyl]pyridine (C21H17NO4). The Eu(III) complex was synthesized by classic chemosynthesis, and also through a solvent-free mechanochemical synthesis, and characterized by spectroscopy, thermal analysis (TGA and DTA), and single crystal X-ray diffraction. The mechanochemical route improves the yield for the complex, which is synthesized over times considerably shorter compared to the traditional synthesis, and through a solvent-free procedure. The photoluminescent properties of the Eu(III) complex and hybrid films P…
Mossbauer spectroscopic studies on the molecular dynamics of organotin(IV) polymers
1981
Abstract Linear organotin(IV) polymers with tin appended to the polymer chain or inserted into the polymer backbone have been characterized by Mossbauer spectroscopy. The lattice dynamics of three representative examples of these classes, as well as of a cross-linked organotin(IV) polymer, have been investigated by temperature-dependent Mossbauer spectroscopy. It has been shown that parameters associated with polymers having low interchain interactions practically correspond to those of molecular, non-coupled, solids.
Junction Dynamics in Telechelic Hydrogen Bonded Polyisobutylene Networks
1996
4-Urazoylbenzoic acid groups are attached to the chain ends of polyisobutylene. The cooperative assembling process of these polar groups is studied by DSC and dielectric and dynamic mechanical spectroscopy. The melting of the ordered clusters occurs in the temperature range 380-390 K. Distortions within the U4A clusters (Σ process) are monitored below the melting temperature T m with dielectric spectroscopy. On a larger length scale, these distortions also lead to stress relaxation which can be probed by dynamic mechanical measurements. Near T m , the relaxation ofU4A multiplets (α* relaxation) is detected with dielectric spectroscopy. In this temperature range, dynamic mechanical measureme…
1H and13C n.m.r. spectra of dichloro(trans-2-chlorovinyl)arsine
1977
Proton and carbon magnetic resonance spectra of Lewisite or dichloro(trans-2-chlorovinyl)arsine have been measured and the results are compared with the n.m.r. spectral parameters of other trans-1,2-substituted ethylenes. The coupling constants can be rationalized by substituent electronegativity. The chemical shifts show an unusually large paramagnetic effect from the AsCl2 group.
Effect of the metal dilution on the thermal and light-induced spin transition in [FexMn1−x(bpp)2](NCSe)2: When T(LIESST) reaches T1/2
2008
International audience; The thermal and light-induced spin transition in [FexMn1−x(bpp)2](NCSe)2 (bpp = 2,6-bis(pyrazol-3-yl)pyridine) has been investigated by magnetic susceptibility, photomagnetism and diffuse reflectivity measurements. These complexes display a thermal spin transition and exhibit the light-induced excited spin state trapping (LIESST) effect at low temperature. For each mixed-crystal system, the thermal spin transition temperature, T1/2, and the relaxation temperature of the photo-induced high-spin state, T(LIESST), have been systematically determined. It appears that T1/2 decreases with the metal dilution while T(LIESST) remains unchanged, suggesting that the two interco…
Flexible vs Rigid Networks of Two Isoreticular Viologen-Carboxylate based PCPs: the Ligand Size Effect
2018
International audience
He-I and He-II excited photoelectron spectra of cyclohepttatrienetricarbonyl complexes of group via metals
1979
Abstract Photoelectron spectra of Group VIA metal complexes M(CO) 3 (η 6 -C 7 H 8 ) have been assigned using experimental criteria along with quantum-mechanical calculations. A general agreement between computed and measured ionization energies has been found for molecular orbitas mainly ligand in character. Similar correlations do not hold for the highest orbitals, mainly metal d based. The energies associated with ionization processes are, in this case, largely dominated by the relaxation terms. The variations of intensities of these bands on changing the energy of ionizing radiation were of crucial significance in the assignment