EPR and optical properties of impurity centers in low-symmetry crystals

Viswanath, Annamraju Kasi; Radhakrishna, S.

doi:10.1016/0022-3697(91)90067-a

Cited by 15 publications

(7 citation statements)

References 168 publications

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“…The effect becomes appreciable with good 𝜋-bonding ligands. In fact, the values of 𝛽 2 2 follow the general 𝜋-bonding order of ligand donor atoms, sulphur > carbon > nitrogen > chlorine > oxygen. [18] Several EPR correlations have shown that the value of 𝑘 increases as the electronegativity difference between the ligand atom and the metal increases.…”

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confidence: 96%

“…Considering covalent bonding, 𝑘 should depend on the 𝑑-orbital population for the unpaired electron: 𝑘 = 𝛽 2 2 𝑘 0 . Decrease of 𝛽 2 2 arises from delocalization of the electron onto the ligand with the increase in covalent bonding. The effect becomes appreciable with good 𝜋-bonding ligands.…”

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confidence: 99%

“…The calculated band positions shown in Table 3 are in good agreement with the observation. Using energy differences obtained from optical spectrum and EPR data, the bonding parameters 𝛽 2 1 and 𝛾 2 can be estimated with the help of the expressions [21] 𝑔…”

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confidence: 99%

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Electron Paramagnetic Resonance and Optical Absorption of VO ²⁺ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Dwivedi¹,

Kripal²,

Shukla³

2010

Chinese Phys. Lett.

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We investigate the electron paramagnetic resonance (EPR) of VO 2+ ions in bis (glycinato) Mg (II) monohydrate single crystals at room temperature. Detailed EPR analysis indicates the presence of only one VO 2+ site. The vanadyl complexes are found to take up the substitutional position. The angular variation of the EPR spectra in three planes 𝑎 * 𝑏, 𝑏𝑐 and 𝑐𝑎 * are used to determine principal 𝑔 and 𝐴 tensors. The values of spin Hamiltonian parameters are 𝑔𝑥 = 2.1447 × 10 −4 , 𝑔𝑦 = 1.9974 × 10 −4 , 𝑔𝑧 = 1.9131 × 10 −4 , 𝐴𝑥 = 49 × 10 −4 , 𝐴𝑦 = 60 × 10 −4 , 𝐴𝑧 = 82×10 −4 cm −1 . The optical absorption study is also carried out at room temperature and absorption bands are assigned to various transitions. The theoretical band positions are obtained using energy expressions and a good agreement is found with the experimental data. By correlating EPR and optical data, different molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed.

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confidence: 96%

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confidence: 99%

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Electron Paramagnetic Resonance and Optical Absorption of VO ²⁺ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Dwivedi¹,

Kripal²,

Shukla³

2010

Chinese Phys. Lett.

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“…This indicates that the complexes are fairly covalent. The dimensionless Fermi contact parameter (K) describes the core s-polarization and represents the amount of unpaired electron density at the vanadium nucleus [51]. The values of K obtained using equations ( 5) and (6) for VO 2+ at sites I and II in ZAPH are 0.83 and 0.82, respectively, which are smaller…”

Section: Fermi Contact Term Dipolar-coupling Parameter and Molecular ...mentioning

confidence: 98%

Electron paramagnetic resonance and optical study of VO²⁺-doped zinc ammonium phosphate hexahydrate single crystals

Kripal¹,

Misra²,

Lipiński³

et al. 2012

Phys. Scr.

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Electron paramagnetic resonance (EPR) and optical studies of VO2+ ions in zinc ammonium phosphate hexahydrate ZnNH4PO4·6H2O (ZAPH) single crystals were carried out at room temperature. Analysis of EPR spectra indicates the presence of two distinct VO2+ sites. The angular variations of EPR spectra in three mutually perpendicular planes ab, bc and ca are used to determine the principal axes and values of the tensors g and A. The spin Hamiltonian (SH) parameters are obtained using Schonland's method as: gx = 1.9967, gy = 1.9767, gz = 1.9668, Ax = 62, Ay = 70, Az = 172(×10−4) cm−1 for site I, whereas gx = 1.9998, gy = 1.9820, gz = 1.9698, Ax = 54, Ay = 60, Az = 149(×10−4) cm−1 for site II. The optical absorption study at room temperature is also carried out and the absorption bands are assigned to various transitions. The theoretical band positions are calculated using approximate energy expressions. Good agreement is obtained between theoretical and experimental band positions. By correlating EPR and optical data, various molecular orbital coefficients of the vanadyl ion in the ZAPH lattice are evaluated and the nature of bonding in the crystal is discussed.

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“…Especially, the optical and magnetic properties of the Tutton salts have been extensively studied for these materials doped with some transition-metal (e.g. Cr 3+ , Mn 2+ , Cu 2+ , Ni 2+ ) ions (3)(4)(5)(6)(7)(8). Generally, the above properties or behaviors are sensitive to the local structures and electronic states of the doped transition-metal impurities, which can be analyzed using electron paramagnetic resonance (EPR) technique (9).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the EPR parameters of the rhombic Cu²⁺center in (NH₄)₂Mg(SO₄)₂·6H₂O single crystal

Xiong

Zheng

2015

Radiation Effects and Defects in Solids

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The electron paramagnetic resonance (EPR) parameters (g factors g x , g y , g z and hyperfine structure constants A x , A y , A z ) for Cu 2+ in (NH 4 ) 2 Mg(SO 4 ) 2 ·6H 2 O (DHMS) crystal are theoretically investigated using the high-order perturbation formulas of these parameters. In the calculations, the ligand orbital and spin-orbit coupling for the impurity Cu 2+ are taken into account; the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the EPR parameters with the local structure of the impurity center. The ligand orbital and the spinorbit coupling contributions are included on the basis of the cluster approach. Based on the calculation, the theoretical EPR parameters show good agreement with the observed values. The results are discussed.

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EPR and optical properties of impurity centers in low-symmetry crystals

Cited by 15 publications

References 168 publications

Electron Paramagnetic Resonance and Optical Absorption of VO ²⁺ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Electron Paramagnetic Resonance and Optical Absorption of VO ²⁺ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Electron paramagnetic resonance and optical study of VO²⁺-doped zinc ammonium phosphate hexahydrate single crystals

Investigation of the EPR parameters of the rhombic Cu²⁺center in (NH₄)₂Mg(SO₄)₂·6H₂O single crystal

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EPR and optical properties of impurity centers in low-symmetry crystals

Cited by 15 publications

References 168 publications

Electron Paramagnetic Resonance and Optical Absorption of VO 2+ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Electron Paramagnetic Resonance and Optical Absorption of VO 2+ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Electron paramagnetic resonance and optical study of VO2+-doped zinc ammonium phosphate hexahydrate single crystals

Investigation of the EPR parameters of the rhombic Cu2+center in (NH4)2Mg(SO4)2·6H2O single crystal

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Electron Paramagnetic Resonance and Optical Absorption of VO ²⁺ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Electron Paramagnetic Resonance and Optical Absorption of VO ²⁺ Doped Bis (glycinato) Mg (II) Monohydrate Single Crystals

Electron paramagnetic resonance and optical study of VO²⁺-doped zinc ammonium phosphate hexahydrate single crystals

Investigation of the EPR parameters of the rhombic Cu²⁺center in (NH₄)₂Mg(SO₄)₂·6H₂O single crystal