New experimental features of the field-modulated microwave absorption in high-Tc ceramic superconductors are presented. The proposed model for loss mechanism can explain complicated field and temperature dependences signals.

Cu3(O2C16H23)6.1.2C6H12, containing a Cu36+ core in an equilateral triangle geometry, has been found to be versatile model system for investigating the spin-frustration phenomenon triangular lattice. It affords well-resolved EPR spectra from both of two possible (Stotal = 1/2 and 3/2) spin states core. From 295 100 K, consist triplet, but with central line overlapped by additional, sharp peak, which replaces triplet at 30 K below. The was thus assigned excited state Stotal 3/2, located 324...

Microwave-absorption measurements using a conventional electron-spin resonance spectrometer provide novel leadless technique for the detection of Josephson junctions and their size in superconductive Ba-Y-Cu-O compounds.

The aniline dimer PADPA (= p-aminodiphenylamine = N-phenyl-1,4-phenylenediamine) was polymerized to poly(PADPA) at 25 °C with Trametes versicolor laccase (TvL)/O2 as catalyst and oxidant in the presence of vesicles formed from sodium bis(2-ethylhexyl) sulfosuccinate (AOT) templates. In comparison previously studied polymerization same type enzyme–vesicle system, is much faster, considerably fewer enzymes are required for complete monomer conversion. Turbidity measurements indicate that...

By studying the variation of microwave absorption superconductive GdBa2Cu3O9-y samples with an ESR apparatus, we have detected influence magnetic field on intergrain Josephson currents surface sample. The onset superconductivity is easily detectable as a sharp signal rise. observed evolution intensity below Tc useful indicator improvement superconducting properties Quenched nonsuperconductive showed no at all.

Powder ZnAl2O4 (gahnite) samples doped with 0-100 at% Co were obtained by a sol-gel technique. X-ray powder diffraction was used to characterize the samples. Gahnite are cubic normal spinel structure, space group Fd3̄m. Cobalt doping caused nonuniform increase of unit-cell parameter. The structure gahnite refined Rietveld method. location Co2+ determined EPR spectroscopy. induces inverse at only 4 Co, and inversion parameter increases level. Metal-oxide distances in (Al,Co)O6 octahedra...

A set of four copper(ii) complexes, and (X = Cl, Br; N-(l-leucine methyl ester)-N'-((2-pyridin-2-yl)methyl)oxalamide N-benzyl-N'-((2-pyridin-2-yl)methyl)oxalamide), have been synthesized characterized by X-ray structural analysis, electron paramagnetic resonance (EPR) spectroscopy on single crystals SQUID magnetization measurements. diffraction studies show one-dimensional hydrogen bonded networks dimeric copper(ii)-complexes bridged two halide ions with the metal centers 3.44-3.69 Å apart....

Crystal structures of alkali salts tetrahaolgenosemiquinone anion radical acetone solvates and their solvent-free are determined. p-Semiquinone reveals enhanced aromaticity the ring compared to quinone. A pair π-stacked (p-semiquinone) rings occurs in crystal potassium rubidium tetrachlorosemiquinone tetrabromo analogue. The centroid separation distances about 3.2 Å carbon–carbon contacts between contiguous 0.3 shorter than sum van der Waals radii. spin-coupling two unpaired electrons...

A new type of spectrum was obtained from an inhomogeneously broadened ESR line under multiple modulation when one the frequencies swept. Each spectral appeared to be equivalent individual spin packet line.

A heterometallic coordination polymer {[Cu(bpy)3][Mn2(C2O4)3]·H2O}n (1; bpy = 2,2′-bipyridine) was synthesized using a building-block approach and characterized by IR spectroscopy, single-crystal X-ray diffraction, magnetization measurement, X-band ESR spectroscopy both on single crystal polycrystalline sample. The molecular structure of 1 is made three-dimensional (3D) anionic network [Mn2(C2O4)3]n2n− tris-chelated cations [Cu(bpy)3]2+ occupying the vacancies framework. In compound magnetic...

We present a generalized nuclear spin bath model for embedded electron decoherence in organic solids at low temperatures, which takes the crucial influence from hindered methyl group rotation tunneling into account. This new, quantum many body model, after resolved using cluster correlation expansion method, predicts profiles directly proton relative position and splitting inputs. Decoherence this explain adequately both strongly weakly groups to decoherence: The former accelerates by...

Using a newly devleoped EPR spin-probing methodology, we have measured magnetic penetration depth \ensuremath{\lambda} for ${\mathrm{Tl}}_{2}$${\mathrm{Ba}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{x}}$ and ${\mathrm{Bi}}_{2}$${\mathrm{Ca}}_{2}$${\mathrm{SrCu}}_{2}$${\mathrm{O}}_{\mathrm{x}}$. The temperature dependence of is found to follow the relationship...

Abstract We report about the first Raman spectroscopy study of a vesicle-assisted enzyme-catalyzed oligomerization reaction. The aniline dimer N -phenyl-1,4-phenylenediamine (= p -aminodiphenylamine, PADPA) was oxidized and oligomerized with Trametes versicolor laccase dissolved O 2 in presence sodium bis(2-ethylhexyl)sulfosuccinate (AOT) vesicles (80–100 nm diameter) as templates. conversion PADPA into oligomeric products, poly(PADPA), monitored during reaction by situ spectroscopy. results...

The electron spin-lattice relaxation of 2,2,6,6-tetramethyl-1-piperidine-1-oxyl and 4-oxo-2,2,6,6-tetramethyl-1-piperidine-1-oxyl was measured at temperatures between 5 80 K in crystalline glassy ethanol using $X$-band paramagnetic resonance spectroscopy. experimental data the lowest studied were explained terms electron-nuclear dipolar interaction center localized excitations, whereas higher low-frequency vibrational modes from host matrix Raman processes should be considered. strong impact...

With the view of understanding low frequency (40-50 cm(-1)) motional processes in L-alanine around 4 K, we have carried out heat capacity (CP) and electron spin echo (ESE) measurements on L-alanine-d7. The obtained CP data show so-called boson peak (seen as a maximum CP/T3 versus T plots) temperature region (1.8-20 K). phase memory time, T(M), lattice relaxation T1, probe, first stable alanine radical (SAR1), *CHCH3COOH, been measured between 105 K. rate 1/T1 shows an anomalous increase...