Ram Kripal
University of Allahabad, PHYSICS DEPARTMENT, Faculty Member
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ABSTRACT X-band electron paramagnetic resonance (EPR) studies are carried out on Fe 3? ions doped in ammonium dihydrogen phosphate (ADP) single crystals at room temperature. The crystal field and spin Hamiltonian parameters are evaluated... more
ABSTRACT X-band electron paramagnetic resonance (EPR) studies are carried out on Fe 3? ions doped in ammonium dihydrogen phosphate (ADP) single crystals at room temperature. The crystal field and spin Hamiltonian parameters are evaluated from the resonance lines obtained at different angular rotations. The obtained values of spin Hamiltonian and zero-field parameters of the Fe 3? ion in ADP are: g = 1.994 ± 0.002, |D| = (220 ± 5) 9 10 -4 cm -1 and a = (640 ± 5) 9 10 -4 cm -1 . On the basis of EPR data, the site symmetry of the Fe 3? ion in the crystal is discussed. The Fe 3? ion enters the lattice substi-tutionally replacing the NH 4 ? sites. The optical absorption of the crystal is also studied at room temperature in the wavelength range of 195–925 nm. The energy values of different orbital levels are calculated. The observed bands are assigned as transitions from the 6 A 1g (S) ground state to various excited quartet levels of the Fe 3? ion in a cubic crystalline field. From the observed band positions, Racah interelectronic repulsion parameters (B and C), cubic crystal field splitting parameter (D q) and Trees correction are calculated. There values are: B = 970, C = 1,923, D q = 1,380 cm -1 and a = 90 cm -1 , respectively. On the basis of EPR and optical data, the nature of bonding in the crystal is discussed. The zero-field splitting (ZFS) parameters are also determined theoretically using B kq parameters estimated from the superposition model. The values of ZFS para-meters thus obtained are |D| = (213 ± 5) 9 10 -4 cm -1 and |E| = (21 ± 5) 9 10 -4 cm -1 .
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The superposition model is used to calculate the crystal field parameters (CFPs) of Mn(2+) in Bis (L-asparaginato) Zn (II). The zero field splitting parameters (ZFSPs) D and E are then investigated using perturbation theory and... more
The superposition model is used to calculate the crystal field parameters (CFPs) of Mn(2+) in Bis (L-asparaginato) Zn (II). The zero field splitting parameters (ZFSPs) D and E are then investigated using perturbation theory and microscopic spin Hamiltonian (SH) theory. The calculated ZFS parameters are compared with the experimental values obtained by electron paramagnetic resonance. Both the zero field splitting parameters (ZFSPs) D and E evaluated theoretically are in good agreement with the experimental values. The results support the notion that the Mn(2+) ion occupies interstitial site in Bis (L-asparaginato) Zn (II).
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Abstract X-band electron paramagnetic resonance (EPR) studies are carried out on Fe 3+ ions doped in ammonium dihydrogen phosphate (ADP) single crystals at room temperature. The crystal field and spin Hamiltonian parameters are evaluated... more
Abstract X-band electron paramagnetic resonance (EPR) studies are carried out on Fe 3+ ions doped in ammonium dihydrogen phosphate (ADP) single crystals at room temperature. The crystal field and spin Hamiltonian parameters are evaluated from the resonance lines ...
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The interpretation of g factor of the VO2+ ion doped in defferent single crystals is made using the Stevens model where the symmetry of the crystalline field is tetragonal. The bonding parameters K|| and K┴, choosing the different... more
The interpretation of g factor of the VO2+ ion doped in defferent single crystals is made using the Stevens model where the symmetry of the crystalline field is tetragonal. The bonding parameters K|| and K┴, choosing the different parametric angle β, are determined. The value of K┴ should be less than 0.048 in order to have a better fit to the experimental g values.
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Research Interests: Geology, Materials Science, Doping, Nano, Zinc, and 3 moreZinc Sulfide, Sulfide, and Superposition principle
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The zero field splitting parameters (ZFSPs) D and E of Cr3+ ion doped potassium sodium dl-tartrate tetrahydrate (PSTT), KNaC4H4O6·4H2O are calculated using the superposition model. The theoretically calculated ZFSPs for Cr3+ in PSTT... more
The zero field splitting parameters (ZFSPs) D and E of Cr3+ ion doped potassium sodium dl-tartrate tetrahydrate (PSTT), KNaC4H4O6·4H2O are calculated using the superposition model. The theoretically calculated ZFSPs for Cr3+ in PSTT crystal are compared with the experimental values obtained by electron paramagnetic resonance. Theoretical ZFSPs are in good agreement with the experimental values. The energy band positions of optical absorption spectra of Cr3+ in PSTT single crystal calculated with the CFA package agree well with experimental values.
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The zero field splitting parameter D of Cr(3+) doped in tetra methyl ammonium cadmium chloride (TMCC) is calculated with perturbation formula using microscopic spin Hamiltonian theory and crystal field parameters from superposition model.... more
The zero field splitting parameter D of Cr(3+) doped in tetra methyl ammonium cadmium chloride (TMCC) is calculated with perturbation formula using microscopic spin Hamiltonian theory and crystal field parameters from superposition model. The theoretically calculated ZFS parameter for Cr(3+) in TMCC single crystal is compared with the experimental value obtained by electron paramagnetic resonance (EPR). The local structure distortion is considered to obtain the crystal field parameters. The theoretical study gives the ZFS parameter D similar to that from experiment. However, calculation considering small distortion in local structure around Cr(3+) gives better agreement with the experimental value of ZFS parameter.
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ABSTRACT The superposition model has been used to investigate the substitution of Mn 2+ in ammonium oxalate monohydrate. The zero field splitting parameters D and E calculated by the superposition model are compared with the experimental... more
ABSTRACT The superposition model has been used to investigate the substitution of Mn 2+ in ammonium oxalate monohydrate. The zero field splitting parameters D and E calculated by the superposition model are compared with the experimental values Dexp and Eexp, respectively, for Mn 2+ obtained by electron paramagnetic resonance. Both the zero field splitting parameters D and E calculated theoretically are in good agreement with the experimental values Dexp and Eexp. The result indicates that the Mn 2+ ion substitutes for the NH + 4 ion in ammonium oxalate monohydrate.
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Electron paramagnetic resonance (EPR) study of Cr 3+ doped cesium tetrabromozincate (CTBZ) single crystal is done at room temperature. The hyperfine structure for Cr 53 isotope is also obtained. Two magnetically inequivalent sites for Cr... more
Electron paramagnetic resonance (EPR) study of Cr 3+ doped cesium tetrabromozincate (CTBZ) single crystal is done at room temperature. The hyperfine structure for Cr 53 isotope is also obtained. Two magnetically inequivalent sites for Cr 3+ are observed. The spin Hamiltonian parameters are evaluated as: D = 234×10 -4 cm -1 , E = 69×10 -4 cm- 1 , g = 2.0104, A = 80×10 -4 cm -1 for site I and D = 235×10 -4 cm -1 , E = 70×10 -4 cm -1 , g = 2.0061, A = 82×10 -4 cm -1 for site II, respectively. The optical absorption spectra are recorded at room temperature. The energy values of different orbital levels are determined. The values of various parameters obtained are: B = 602 cm -1 , C = 2504 cm -1 , Dq = 1870 cm -1 , h = 1.63 and k = 0.21, where B and C are Racah parameters, Dq is crystal field parameter, and h and k are nephelauxetic parameters, respectively. Theoretical zero-field splitting (ZFS) parameters for Cr 3+ at two sites in CTBZ are evaluated using superposition model and microscopic spin Hamiltonian theory. The theoretical ZFS parameters are in good agreement with the experimental values.
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ABSTRACT X-band electron paramagnetic resonance (EPR) studies are carried out on Fe 3? ions doped in ammonium dihydrogen phosphate (ADP) single crystals at room temperature. The crystal field and spin Hamiltonian parameters are evaluated... more
ABSTRACT X-band electron paramagnetic resonance (EPR) studies are carried out on Fe 3? ions doped in ammonium dihydrogen phosphate (ADP) single crystals at room temperature. The crystal field and spin Hamiltonian parameters are evaluated from the resonance lines obtained at different angular rotations. The obtained values of spin Hamiltonian and zero-field parameters of the Fe 3? ion in ADP are: g = 1.994 ± 0.002, |D| = (220 ± 5) 9 10 -4 cm -1 and a = (640 ± 5) 9 10 -4 cm -1 . On the basis of EPR data, the site symmetry of the Fe 3? ion in the crystal is discussed. The Fe 3? ion enters the lattice substi-tutionally replacing the NH 4 ? sites. The optical absorption of the crystal is also studied at room temperature in the wavelength range of 195–925 nm. The energy values of different orbital levels are calculated. The observed bands are assigned as transitions from the 6 A 1g (S) ground state to various excited quartet levels of the Fe 3? ion in a cubic crystalline field. From the observed band positions, Racah interelectronic repulsion parameters (B and C), cubic crystal field splitting parameter (D q) and Trees correction are calculated. There values are: B = 970, C = 1,923, D q = 1,380 cm -1 and a = 90 cm -1 , respectively. On the basis of EPR and optical data, the nature of bonding in the crystal is discussed. The zero-field splitting (ZFS) parameters are also determined theoretically using B kq parameters estimated from the superposition model. The values of ZFS para-meters thus obtained are |D| = (213 ± 5) 9 10 -4 cm -1 and |E| = (21 ± 5) 9 10 -4 cm -1 .
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Abstract Electron paramagnetic resonance (EPR) study of Cu 2+ doped lithium maleate dihydrate single crystal is done at liquid nitrogen temperature (LNT). Four hyperfine lines are observed in all directions, i.e. only a single site is... more
Abstract Electron paramagnetic resonance (EPR) study of Cu 2+ doped lithium maleate dihydrate single crystal is done at liquid nitrogen temperature (LNT). Four hyperfine lines are observed in all directions, i.e. only a single site is observed. The spin Hamiltonian parameters are determined from EPR spectra: g x =2.100±0.002, g y =2.162±0.002, g z =2.215±0.002, A x =(55±5)×10 −4 cm −1 , A y =(52±5)×10 −4 cm −1 , A z =(50±5)×10 −4 cm −1 . The results indicate that the copper ion enters the lattice interstitially. Using the spin Hamiltonian parameters obtained from EPR study the ground state wave function of Cu 2+ ion in the lattice is determined. The optical absorption study of Cu 2+ doped lithium maleate dihydrate at room temperature is also performed. With the help of optical and EPR data, the nature of bonding in the complex is discussed.
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Electron spin resonance (ESR) of Cu2+ doped calcium propionate has been studied at room temperature. Spin Hamiltonian parameters are calculated from the ESR absorption spectra which are gx=2.1285±0.002, gy=2.1868±0.002, gz=2.2205±0.002,... more
Electron spin resonance (ESR) of Cu2+ doped calcium propionate has been studied at room temperature. Spin Hamiltonian parameters are calculated from the ESR absorption spectra which are gx=2.1285±0.002, gy=2.1868±0.002, gz=2.2205±0.002, Ax=(121±2)×10-4 cm-1, Ay=(140±2)×10-4 cm-1 and Az=(142±2)×10-4 cm-1. It is found that Cu2+ enters the lattice interstitially. The ESR results indicate that the copper complex possesses rhombic symmetry. The ground state wave function of Cu2+ ion in this lattice is also determined from the spin-Hamiltonian constants obtained from ESR results. It is found that the ground state is predominantly |x2-y2>.
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Electron paramagnetic resonance (EPR) study of Fe3+ ion-doped dipotassium stannic chloride (K2SnCl4·H2O, DPSC) single crystal is performed at X band frequency and liquid nitrogen temperature. The Zeeman g-factor, axial zero-field... more
Electron paramagnetic resonance (EPR) study of Fe3+ ion-doped dipotassium stannic chloride (K2SnCl4·H2O, DPSC) single crystal is performed at X band frequency and liquid nitrogen temperature. The Zeeman g-factor, axial zero-field splitting parameters and rhombic zero-field splitting parameters of Fe3+ ion in DPSC are determined with the help angular dependence of EPR spectra. Fe3+ ion enters the crystal lattice substitutionally replacing the K+ ion. The optical absorption spectra are recorded at room temperature in the wavelength range 195–1,100 nm. The transitions are assigned from the ground state $${}^{6}{\text{A}}_{{1{\text{g}}}} \left( {\text{S}} \right)$$6A1gS to different excited states of Fe3+ ion. The observed band positions fitted by four parameters, Racah inter-electronic repulsion parameters (B and C), cubic splitting parameters (Dq) and Trees correction (α) yield: B = 831 cm−1, C = 2,198 cm−1, Dq = 820 cm−1, and α = 90 cm−1.
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The electron paramagnetic resonance study of Cu2?-doped bis(L-as-paraginato)Mg(II) is performed at room temperature. Two magnetically non-equivalent sites for Cu2? are observed. The spin-Hamiltonian parameters evaluated by fitting spectra... more
The electron paramagnetic resonance study of Cu2?-doped bis(L-as-paraginato)Mg(II) is performed at room temperature. Two magnetically non-equivalent sites for Cu2? are observed. The spin-Hamiltonian parameters evaluated by fitting spectra to ...