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Journal ArticleDOI

Electronic transitions of nickel(II) ions in cadmium ammonium sulphate hexahydrate single crystals

01 Oct 1987-Solid State Communications (Pergamon)-Vol. 64, Iss: 4, pp 561-565

Abstract: The optical absorption spectra of Cd(NH 4 ) 2 (SO 4 ) 2 ·6H 2 O doped Ni 2+ at 300 and 80 K was recorded. The Dq, B and C parameters at 300 and 80 K are calculated and the transitions are assigned. The fine structure of Cd(NH 4 ) 2 (SO 4 ) 2 ·6H 2 O doped Ni 2+ are observed at 80 K from the well resolved double peaked red band. Finally, the matrices for the energy levels with spin orbit coupling are diagonalised and the experimental values were fitted with the theoretically calculated values. The oscillator strengths of the transitions were computed from the area under the curves. The best fit was obtained for the values of the crystal field parameters Dq = 892cm -1 , B = 940cm -1 , C = 3760cm -1 and λ = - 260cm -1 at 300 K and Dq = 922cm -1 , B = 955cm -1 , C =4202cm -1 and λ=-275cm -1 at 80K respectively.
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Journal ArticleDOI
Abstract: Optical absorption spectrum of Cr3+ ions doped in sodium ammonium sulphate dihydrate single crystal has been studied both at room and liquid nitrogen temperatures The observed bands were explained satisfactorily assuming octahedral symmetry for the Cr3+ ion in the crystal The crystal field parameters Dq = 1750 cm−1, B = 735 cm−1 and C = 3220 cm−1 are found to give a good fit to the observed band positions

2 citations


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Journal ArticleDOI
Donald S. McClure1Institutions (1)
Abstract: Crystal field theory in conjunction with spectroscopic data may be applied to give quantitatively the d-shell splitting and the resulting stabilization of a transition metal ion in a crystal site of given symmetry. The thermodynamic stabilization values are found for both octahedral and tetrahedral sites in the spinel lattice. The differences between these values is the site preference energy. The cation distributions predicted from this energy are in good agreement with known experimental data. The occurrence of a large Jahn-Teller effect is correlated with tetragonal phase formation.

400 citations


Journal ArticleDOI
Abstract: The absorption spectra of crystalline hydrates of the first transition group ions have been measured with polarized light at room temperature, and with unpolarized light at a series of lower temperatures. Some new data on solution spectra have also been obtained. The values of Dq for these compounds are obtained, and are used to explain irregularities in the heats of hydration of the ions. The temperature dependence of the spectra shows that the transitions are vibration‐induced electric‐dipole transitions for the most part. The dichroism has been used to resolve some of the bands and to determine the effect of noncubic components of the crystal field.

350 citations


Journal ArticleDOI
Abstract: The infra‐red spectra of thin non‐scattering films of NH4Cl and ND4Cl were obtained at 28°, −78° and −190°C. A convenient low temperature transmission type cell usable for such films is described. No indication of fine structure due to free rotation of the NH4+ ions was found. Instead, evidence is presented for the existence, both above and below the λ‐point, of a torsional lattice mode involving the NH4+ ions. The limiting frequencies of the torsional oscillations were observed at about 390 and 280 cm−1 for NH4Cl and ND4Cl, respectively. These values agree quite well with the frequencies calculated on the basis of a purely electrostatic potential function. The spectra of the low temperature modifications indicate strongly that the structures belong to the space group Td1 in which the NH4+ ion symmetry is Td. Of the eight observed bands, two are assigned to the triply degenerate fundamentals ν3 and ν4, one to the overtone 2ν4, one to the combination ν2+ν4 which resonates strongly with ν3, one to the combi...

319 citations



Journal ArticleDOI
Andrew D. Liehr1, C.J. Ballhausen1Institutions (1)
Abstract: The generalized crystal field theory of Finkelstein and Van Vleck is augmented by the introduction of spin-orbit coupling and an attempt is made to thus account for both the spin-allowed and the spin-forbidden dn, (n = 2, 8), spectral transitions of Ni(II) and V(III) complexes. The secular equations are derived by the use of functions which span, in both the weak and strong crystalline field pictures, the proper spin-coordinate cubic symmetry classification of Bethe. These secular equations were solved numerically on the IBM 704 data processing machine at the Murray Hill Bell Telephone Laboratories and the results are illustrated by suitable graphs. The existing spectral data on tetrahedral and octahedral complexes of Ni(II) and V(III) have been interpreted theoretically and it is found that the calculations do not support Jorgensen's assignment of the double-peaked red band of hexaquo nickel systems. Spinallowed infrared transitions are predicted at ∼350, 1000, 1100, and 5300 cm−1 for tetrahedral Ni(II) complexes and at ∼1.6, 168, and 250 cm−1 for octahedral V(III) complexes. Low's spectral data on divalent nickel dissolved in magnesium oxide and trivalent vanadium dissolved in aluminum oxide are given a rigorous theoretical interpretation. Some comments on the applicability of the derived transformation and energy matrices to the related magnetic problems (paramagnetic resonance and magnetic susceptibilities) and spectral problems (energy level splittings due to fields of lower symmetry) are given in the appendices. In particular, it is shown that the ground electronic state splitting of 0.49 cm−1 found by Holden et al. in nickel fluosilicate hexahydrate implies a 50-cm−1 trigonal field splitting of certain of the excited electronic states.

216 citations