Optical Absorption Spectrum Of Ni2 Research Articles

Ab initio model potential calculations on the electronic spectrum of Ni2+-doped MgO including correlation, spin–orbit and embedding effects

An ab initio theoretical study of the optical absorption spectrum of Ni2+-doped MgO has been conducted by means of calculations in a MgO-embedded (NiO6)10−cluster. The calculations include long- and short-range embedding effects of electrostatic and quantum nature brought about by the MgO crystalline lattice, as well as electron correlation and spin–orbit effects within the (NiO6)10− cluster. The spin–orbit calculations have been performed using the spin–orbit-CI WB-AIMP method [Chem. Phys. Lett. 147, 597 (1988); J. Chem. Phys. 102, 8078 (1995)] which has been recently proposed and is applied here for the first time to the field of impurities in crystals. The WB-AIMP method is extended in order to handle correlation effects which, being necessary to produce accurate energy differences between spin–free states, are not needed for the proper calculation of spin–orbit couplings. The extension of the WB-AIMP method, which is also aimed at keeping the size of the spin–orbit-CI within reasonable limits, is based on the use of spin-free-state shifting operators. It is shown that the unreasonable spin–orbit splittings obtained for MgO:Ni2+ in spin–orbit-CI calculations correlating only 8 electrons become correct when the proposed extension is applied, so that the same CI space is used but energy corrections due to correlating up to 26 electrons are included. The results of the ligand field spectrum of MgO:Ni2+ show good overall agreement with the experimental measurements and a reassignment of the observed Eg(b3T1g) excited state is proposed and discussed.

Optical absorption spectrum of Ni2+ions in sodium ammonium sulphate dihydrate single crystal

Optical absorption spectrum of Ni²⁺ions in sodium ammonium sulphate dihydrate single crystal

Optical absorption spectrum of Ni2+ ions in ammonium dihydrogen phosphate

Results of optical absorption studies on Ni2+ ions doped in ammonium dihydrogen phosphate single crystal at RT are reported. The spectrum shows characteristic features of Ni2+ ions in octahedral crystalline fields. From a detailed analysis of the spectrum, the crystal field parameters B, C and Dq are evaluated.

Electron paramagnetic resonance and polarized optical absorption spectra of Ni2+ in synthetic forsterite

The investigated Ni doped forsterite was grown with the floating zone technique. The EPR spectra were taken at room temperature using both 9.5 and 35 GHz. All specimens show EPR signals resulting from Mn2+ at M2 and Fe3+ at M1, M2, and Si positions. Ni2+ EPR signals are observed at 35 GHz but not at 9.5 GHz. The Ni2+ spectra are described by the spin Hamiltonian $$H = \beta SgB + D\left( {S_{\text{z}}^{\text{2}} - \left( {S + 1} \right)S/3} \right) + E\left( {S_{\text{x}}^{\text{2}} - S_{\text{y}}^{\text{2}} } \right)$$ with S=1. The EPR parameters obtained are: D=−39.56 cm−1, E=−0.58 cm−1, gx=2.194, gy=2.160, gz=2.188. Polarized optical absorption spectra of Ni2+ were taken at room and liquid nitrogen temperature covering the range from 5500 to 42000 cm−1. The spectra are nearly independent of the polarization of light. Both EPR and optical spectra reveal that Ni2+ is ordered into M1. The local symmetry of the Ni(M1) complex is described by the point group D2h with the main symmetry axis along a. Heating experiments in air up to 1000° C and three days indicated no change in the Ni ordering in this synthetic sample.

Optical Absorption Spectra of Ni<sup>2+</sup> Ions and IR Spectra in (100-<i>x</i>) (PbO⋅GeO<sub>2</sub>)⋅<i>x</i>RO (R=Mg, Ca, Sr, Ba) Glasses

Optical absorption spectra of Ni2+ ion (100-x) (PbO⋅GeO2)⋅xRO⋅0.2wt% NiO glasses are measured, and the results are obtained as follows.The value of 10Dq which represents the intensity of the ligand field shifts toward higher wave number with increasing alkaline earth metal content. The increasing intensity of the ligand field is considered to be the formation of GeO68-, where the glass network was destroyed by alkaline earth metals. In this study, the ν4 peak appears only at 20mol% BaO, which represents a Ni2+ ion with 4-coordination. In other systems the ν4 peak does not appear clearly. It is considered that the Ni2+ ion does not become 4-coordination.According to the measurements of infrared spectra, most of this system consists of Ge6 groups, and the variation of coordination number of Ge with the alkaline earth metal contents hardly appear.

Crystal Field and Spin-Orbit Effects in the Optical Spectrum of Ni2+Ions Doped in Ammonium Aluminium Sulphate Single Crystal

Abstract The optical absorption spectrum of Ni2+ ions doped in ammonium aluminium sulphate single crystal has been studied at room and liquid air temperatures. From the nature and otner details of the spectrum, the crystal is found to have an octahedral symmetry. The fine splitting of the 3T1g (F) band at liquid air temperature has been interpreted due to spinorbit interaction. A weak band observed at 16845 cm−1 has been assigned to the vibrational mode of SO4 molecule. From a detailed analysis of the bands of the spectrum, the crystal parameters derived are: B = 678 cm−1; C = 3.75 B; Dq = 1030 cm−1 and ξ = 600 cm−1

Absorption spectrum of Ni2+ doped in NH4Br single crystal

The optical absorption spectrum of Ni2+ doped in NH4Br single crystals has been studied at room and liquid-air temperatures. The observed ambient bands at 6300, 11,600, 13,400, 18,500, and 20,000 cm−1 have been assigned, respectively, to the transitions3A2(F) →3T2(F),3T1(F),1E(D),1T2(D and3T1(P). The crystal field parameters evaluated areDq=630 cm−1,B=850 cm−1, andC=3600 cm−1. In assigning the location of Ni2+ ions within the lattice, evaluations are made of the (limited) extant comparable data. It is then concluded that Ni2+ enters an octahedral interstitial, rather than a substitutional, site. It is surrounded by four bromide ions, in a plane, with two polarized water molecules at the opposing fifth and sixth positions.

Absorption Spectrum of Ni2+in K2Zn(SO4)2·6H2O

Abstract The optical absorption spectrum of Ni2+ in potassium zinc sulphate hexahydrate single crystal has been studied at room and liquid nitrogen temperatures. From the nature and position of the observed bands, a successful interpretation could be made assuming octahedral symmetry for the Ni2+ ion in the crystal. The splitting of 3T1g (F) band at liquid nitrogen temperature has been interpreted as due to spin-orbit interaction. The extra band observed at 16325 cm−1 at liquid nitrogen temperature has been explained to be the superposition of vibrational mode of SO2− 4 radical on 3T1g (F) band.

Optical absorption spectrum of Ni2+ ion doped in synthetic lecontite

The optical absorption spectrum of Ni2+ ion doped in lecontite (sodium ammonium sulphate dihydrate) single crystal has been studied at room and liquid air temperatures. All the bands could be assigned assumingOh symmetry for the Ni2+ ion in the crystal. The splitting of3T1g (F) band at liquid air temperature has been attributed to spin-orbit interaction. The crystal field and spin-orbit parameters derived areDq=1000 cm−1;B=740 cm−1;C/B=4.27 and ζ=600 cm−1. All the bands observed show a blue shift when the crystal was cooled to liquid air temperature.

Optical absorption spectrum of Ni2+ doped in ammonium zinc sulphate

The optical absorption spectrum of Ni2+ ion doped in ammonium zinc sulphate has been studied at room and liquid air temperatures. From the nature and the positions of the bands a successful interpretation of all the bands could be made assumingOh symmetry for the Ni2+ ion in the crystal. The fine splitting of the3T11 band at liquid air temperature has been successfully interpreted to be due to spin-orbit interaction. The crystal field and spin-orbit parameters derived areDq=1000 cm−1;B=750 cm−1;C=3.45B andξ=600 cm−1.

Optical Spectra of Nickel and Chromium in Various Binary Glasses

Optical absorption spectra of Ni2+ and Cr3+ have been determined over the range 350∼2500nm in binary silicate, borate, phosphate and germanate glasses.The values of the crystal field strength Dq and the Racah parameters B and C for the glasses were calculated from the observed band positions. The assignments for the bands ν1∼ν5 and νT1 of Ni2+ and Cr3+ in these glasses were made and the calculated band positions of ν1∼ν5 were determined as shown in Table I. The increase of Dq in the composition range of approximately 25∼45mol. per cent PbO for the lead-borate glass is interpreted based on the evidences that the four-co-ordinated borons are present and the type of lead-oxygen association becomes more covalent bonding.

Optical absorption spectrum of Ni2+ in Garnierite

The results obtained in the study of the absorption spectrum of Ni2+ in two samples of Garnierite are described. Both the samples of Garnierite have been studied by preparing their mineral oil mulls. One of these samples could however be studied in its crystal form as well. From the observed features, the absorption bands in both the samples of Garnierite have been attributed to an ion of Ni2+ in tetrahedral symmetry. The observed and calculated energies for the bands are found to be in close agreement with one another justifying the assumption that the site symmetry of Ni2+ ion is tetrahedral. For one of the Garnierite samples both the crystal and mineral oil mull spectra could be recorded and it is interesting to find that they are identical with one another. It has therefore been suggested that the absorption spectrum of any mineral can be studied by preparing its mineral oil mull in case it cannot be cut and polished into a thin crystal suitable for absorption work. The crystal field parameters derived for the two samples of Garnierite are identical and they are B = 845 cm−1, C = 3.9 B, Dq = 422 cm−1 and λ = − 275 cm−1.