scholarly journals Thieno[3,2-c]Pyridine Complex of Ni(II) with Unusual Magnetic Properties

2016 ◽  
Vol 15 (2) ◽  
pp. 182-189 ◽  
Author(s):  
Jozef Miklovič ◽  
Peter Baran ◽  
Roman Boča
Keyword(s):  
Magnetic Moment ◽  
Effective Magnetic Moment ◽  
Room Temperature ◽  
Nickel Atom ◽  
Free Form ◽  
Zero Field ◽  
Aromatic Rings ◽  
Zero Field Splitting ◽  
Pyridine Complex ◽  
Tetragonal Bipyramid

AbstractThieno[3,2-c]pyridine (thpy) has been prepared in a free form and embodied into the [Ni(thpy)2(H2O)2(ac)2] complex as a ligand. The X-ray structure shows a molecular structure of the complex with Ni−O(ac) = 2.059, Ni−OH2 = 2.078, and Ni−N(thpy) = 2.124 Ǻ. Electronically the complex behaves like a compressed tetragonal bipyramid. The molecular units are linked into a complex system of hydrogen bonds. Two units show a π−π stacking of the aromatic rings (3.8 Ǻ). There are planes of tetragons formed of the nickel atom with the in-plane Ni...Ni separation of 7.74 Ǻ and the inter-plane Ni...Ni contacts at a = 9.65 Ǻ. The effective magnetic moment shows a gradual decrease on cooling from the room temperature and an abrupt drop below 20 K typical for the zero-field splitting of S = 1 systems. Above the room temperature the effective magnetic moment shows anomalies – a decrease and then an increase.

The EPR Zero-Field Splitting D and its Pressure and Temperature Dependence for Trigonal Mn2+ Centers in [Zn(H2O)6](BF4)2:Mn2+ Crystal

2006 ◽  
Vol 61 (5-6) ◽  
pp. 289-292 ◽  
Author(s):  
Hong-Gang Liu ◽  
Xiao-Xuan Wu ◽  
Wen-Chen Zheng ◽  
Lv He
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Coupling Mechanism ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Thermal Expansion Coefficients ◽  
Perturbation Formula ◽  
Expansion Coefficients

The EPR zero-field splitting D (= b02 ) and its pressure and temperature dependence for trigonal Mn2+ centers in low and room temperature phases in [Zn(H2O)6](BF4)2 :Mn2+ crystal are studied by a high-order perturbation formula based on the dominant spin-orbit coupling mechanism. From the studies, the local trigonal distortion angles, the local angular compressibilities and the local angular thermal expansion coefficients for Mn2+ centers in both phases of the [Zn(H2O)6](BF4)2 crystal are estimated. The results are discussed

scholarly journals Abnormal Magnetic Moment and Zero Field Splitting of Some Nickel (II) Complexes

2017 ◽  
Vol 7 (1) ◽  
pp. 34
Author(s):  
Rajeev Ranjan ◽  
Navneet Sinha ◽  
Sahdeo Kumar ◽  
Chandra Mauleshwar Chandra ◽  
Shivadhar Sharma
Keyword(s):  
Magnetic Moment ◽  
Metal Ion ◽  
Free Ligand ◽  
Tetragonal Distortion ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Absorption Bands ◽  
Field Splitting ◽  
Zero Field Splitting Parameter ◽  
Splitting Parameter

<em>Some complexes of Ni(II) have been prepared with 2-thio-3-acetyl hydantoin (TAHN) and 2-formyl pyridine thiosemicarbazone (FPTS). On the basis of elemental analysis and molar conductivity, the complexes have been formulated as NiL<sub>2</sub>X<sub>2</sub>, where L = TAHN or FPTS and X = Cl<sup>–</sup>, Br<sup>–</sup>, NCS<sup>–</sup>, ClO<sub>4</sub><sup>–</sup>. The infrared spectra of complexes and free ligand reveal that the ligand TAHN is co-ordinated through sulphur and acetyl oxygen, while FPTS ligand co-ordinates through heterocyclic nitrogen and sulphur to Ni(II) metal ion. The magnetic moment of these complexes are found to be 3.20-3.25 B.M. The values are greater than value (2.828 B.M) corresponding to two unpaired electrons of a d<sup>8</sup>-system. The appearance of four absorption bands in their electronic spectra reveal, the tetragonal distortion in the octahedral symmetry of complexes. The zero field splitting parameter(D) and the other crystal field parameters like Dq<sub>(xy)</sub>, Dq<sub>(z)</sub>, Dt have been calculated. The results show that, the tetragonal distortion parameter (Dt) increases in the order of NCS<sup>– </sup>&lt; Cl<sup>–</sup> &lt; Br<sup>–</sup> while the zero field splitting parameter (D) also increases in the same order for both the planer ligands.</em>

scholarly journals Pentacene in 1,3,5-Tri(1-naphtyl)benzene: A Novel Standard for Transient EPR Spectroscopy at Room Temperature

2021 ◽  
Author(s):  
Mirjam Schröder ◽  
Daniel Rauber ◽  
Clemens Matt ◽  
Christopher W. M. Kay
Keyword(s):  
Epr Spectroscopy ◽  
Room Temperature ◽  
Glass Transition Point ◽  
Zero Field ◽  
Microwave Resonator ◽  
Spectral Simulation ◽  
Zero Field Splitting ◽  
Standard Samples ◽  
Epr Spectrum ◽  
Data Set

AbstractTesting and calibrating an experimental setup with standard samples is an essential aspect of scientific research. Single crystals of pentacene in p-terphenyl are widely used for this purpose in transient electron paramagnetic resonance (EPR) spectroscopy. However, this sample is not without downsides: the crystals need to be grown and the EPR transitions only appear at particular orientations of the crystal with respect to the external magnetic field. An alternative host for pentacene is the glass-forming 1,3,5-tri(1-naphtyl)benzene (TNB). Due to the high glass transition point of TNB, an amorphous glass containing randomly oriented pentacene molecules is obtained at room temperature. Here we demonstrate that pentacene dissolved in TNB gives a typical “powder-like” transient EPR spectrum of the triplet state following pulsed laser excitation. From the two-dimensional data set, it is straightforward to obtain the zero-field splitting parameters and relative populations by spectral simulation as well as the $$B_{1}$$ B 1 field in the microwave resonator. Due to the simplicity of preparation, handling and stability, this system is ideal for adjusting the laser beam with respect to the microwave resonator and for introducing students to transient EPR spectroscopy.

Fine Structure of Triplet Centers in Room Temperature Irradiated 6H-SiC

2010 ◽  
Vol 645-648 ◽  
pp. 403-406 ◽  
Author(s):  
Andreas Scholle ◽  
Siegmund Greulich-Weber ◽  
Eva Rauls ◽  
Wolf Gero Schmidt ◽  
Uwe Gerstmann
Keyword(s):  
Fine Structure ◽  
Room Temperature ◽  
Positive Sign ◽  
Spin Interaction ◽  
Zero Field ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Defect Center ◽  
Field Splitting ◽  
Annealing Behavior

In non-annealed 6H-SiC samples that were electron irradiated at room temperature, a new EPR signal due to a S=1 defect center with exceptionally large zero-field splitting (D = +652•10-4 cm-1) has been observed under illumination. A positive sign of D demonstrates that the spin-orbit contribution to the zero-field splitting exceeds by far that of the spin-spin interaction. A principal axis of the fine structure tilted by 59° against the crystal c-axis as well as the exceptionally high zero-field splitting D can be qualitatively understood by the occurrence of additional close-lying defect levels in defect clusters resulting in comparatively large second-order spin-orbit coup¬ling. A tentative assignment to vacancy clusters is supported by the observed annealing behavior.

ESR SPECTRA OF Fe+3 IN SINGLE CRYSTALS OF ANDALUSITE

1966 ◽  
Vol 44 (3) ◽  
pp. 509-523 ◽  
Author(s):  
F. Holuj ◽  
J. R. Thyer ◽  
N. E. Hedgecock
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Esr Spectra ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
K Band

ESR spectra of Fe+3 in andalusite have been investigated at X- and K-band frequencies at room temperature. They have been interpreted on the assumption that Fe+3 occupies the two inequivalent Al+3 sites in andalusite. The spectra show large zero-field splitting. The constants of the conventional orthorhombic spin Hamiltonian which fit the spectra are as follows: for site I: b20 = 15.0 ± 0.1 kG, b22 = 5.0 ± 0.1 kG, and isotropic g = 2.001 ± 0.002; for site II: b20 = 20.1 ± 0.1 kG, b22 = 0.075 ± 0.010 kG, and isotropic g = 2.004 ± 0.0005. A study of the intensities of ESR signals due to site I follow a pattern predicted by theory. The implications of these results are considered briefly.

ELECTRON SPIN RESONANCE OF Fe+3 IN CORDIERITE

1966 ◽  
Vol 44 (11) ◽  
pp. 2749-2755 ◽  
Author(s):  
N. E. Hedgecock ◽  
S. C. Chakravartty
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Room Temperature ◽  
Esr Spectra ◽  
Orthorhombic Symmetry ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Spin Resonance

ESR spectra of Fe+3 located at one of the aluminium sites in cordierite have been investigated at X- and K-band frequencies at room temperature. The spectra exhibit large zero-field splitting and have been fitted to a spin Hamiltonian of orthorhombic symmetry, having constants b20 = 14.6 ± 0.1 kG, b22 = 8.5 ± 0.1 kG, and isotropic g = 2.004 ± 0.002.

Atomic-Scale Defects in Silicon Carbide for Quantum Sensing Applications

2015 ◽  
Vol 821-823 ◽  
pp. 355-358
Author(s):  
Vladimir Dyakonov ◽  
Hannes Kraus ◽  
V.A. Soltamov ◽  
Franziska Fuchs ◽  
Dmitrij Simin ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Room Temperature ◽  
Atomic Scale ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Crystal Fields ◽  
Quantum Properties ◽  
Sensing Applications ◽  
Quantum Sensing ◽  
Thermal Shift

Atomic-scale defects in silicon carbide exhibit very attractive quantum properties that can be exploited to provide outstanding performance in various sensing applications. Here we provide the results of our studies of the spin-optical properties of the vacancy related defects in SiC. Our studies show that several spin-3/2 defects in silicon carbide crystal are characterized by nearly temperature independent axial crystal fields, which makes these defects very attractive for vector magnetometry. The zero-field splitting of another defect exhibits on contrast a giant thermal shift of 1.1 MHz/K at room temperature, and can be used for temperature sensing applications.

Photoluminescence Processes in the Triplet State of Phosphorescent Organic Materials: Ir(ppy)3 Doped in TPD

2006 ◽  
Vol 517 ◽  
pp. 173-182
Author(s):  
Nadeer Aljaroudi ◽  
Taiju Tsuboi
Keyword(s):  
Triplet State ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Energy Diffusion ◽  
Temperature Dependences ◽  
Level Model ◽  
Pl Intensity ◽  
Good Agreement

Photoluminescence (PL) measurements have been made for a spin-coated thin film of phosphorescent tris(2-phenylpyridine) iridium [Ir(ppy)3] doped in N,N’-bis (3-methylphenyl)-N, N’-bis(phenyl)-benzidine (TPD) host material in the temperature range from 10 K to room temperature. When temperature is increased from 10 K to 300 K, the PL intensity of Ir(ppy)3 increases from 10 K and decreases above about 200 K. Theoretical calculations are undertaken for the temperature dependence using (1) a three-level model where three zero-field splitting substates are generated in the triplet state of Ir(ppy)3 and (2) endothermic energy transfer from the TPD host to the Ir(ppy)3 guest, and (3) energy diffusion from the excited TPD to the neighboring unexcited TPD. A good agreement was obtained between the measured and calculated temperature dependences of the PL intensity.

Magnetic moments of copper(II) complexes

1958 ◽  
Vol 11 (4) ◽  
pp. 406 ◽  
Author(s):  
K Ito ◽  
T Ito
Keyword(s):  
Molecular Orbital ◽  
Magnetic Moment ◽  
Effective Magnetic Moment ◽  
Room Temperature ◽  
Magnetic Moments ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Orbital Contribution ◽  
Square Planar

Magnetic moments of octahedral, tetrahedral, square planar, trigonal planar, and trigonal pyramidal Cu(II) complexes have been discussed theoretically including the orbital contribution on the basis of the molecular orbital theory. It has been shown that the orbital contribution of electrons to the magnetic moment is expected only in tetrahedral, trigonal planar, and trigonal pyramidal complexes. The effective magnetic moment of tetrahedral Cu(II) complexes has been estimated to be about 2.2 at room temperature and that of tri-coordinated Cu(II) complexes to be higher than the spin-only value. The hypothesis of electron promotion to a 4p level in Cu(II) complexes has been criticized.

Investigations of the EPR Parameters and Local Structures for Two Tetragonal Cr3+ Centers in NH4Cl Crystal

2001 ◽  
Vol 56 (3-4) ◽  
pp. 326-328 ◽  
Author(s):  
Shao-Yi Wu ◽  
Wen-Chen Zheng
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Room Temperature ◽  
Zero Field ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Resonance Parameters ◽  
Local Structures ◽  
Epr Parameters ◽  
Electron Paramagnetic

Abstract In this paper, the zero-field splittings D and g factors g||, g⟂ at room temperature for two tetragonal Cr3+ centers in NH4Cl:Cr3+ crystal have been investigated by a two-spin-orbit (S.O)-parameter model, in which both the contribution due to the S.O. coupling of central d3 ion and that of ligands are considered. From the investigations, the signs of zero-field splitting and the local structures of both centers are ob­ tained. The electron paramagnetic resonance parameters D, g|| and g⟂ of both centers are also explained.

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