Tanabe-Sugano Diagram Research Articles

Interpretation of the Emission Spectra of Trivalent Chromium-Doped Garnet Crystals Using Tanabe-Sugano Diagrams

The purpose of this paper is to provide an example of a real-world application in which Tanabe-Sugano diagrams can be used to relate the optical properties and performance of a material to its physical and chemical properties. Tanabe-Sugano diagrams illustrate the effect of the strength of the octahedral ligand field on the relative positions of the various energy level components that arise as a result of the splitting of the degenerate free-ion states. The application of these diagrams can also be extended to the spectra of transition metal ions found in solid state matrices where the predominant external force is the crystal field. In insulating materials, transition metal ions occupy sites with six anions as nearest-neighbors, forming a coordination sphere characterized as a distorted octahedron. Although the actual site symmetry is lower than Oh in most cases, an octahedral approximation is qualitatively sufficient for the present application involving an analysis and interpretation of the emission spectra of chromium-doped garnets.

Electron Paramagnetic Resonance: Elementary Theory and Practical Applications

Basic Principles of Electron Paramagnetic Resonance Magnetic Interactions Between Particles Isotropic Hyperfine Effects in EPR Spectra g-Anisotropy in Solids Hyperfine Anisotropy in Solids Systems with More than One Unpaired Electron Paramagnetic Species in Gas Phase Transition-Group Ions The Interpretation of EPR Parameters Relaxation Times, Linewidths and Kinetic Phenomena Time-Dependent Excitation of Spins Double-Resonance Techniques Other Topics.

Spectra of tetravalent chromium in calcium fluorophosphate

The spectroscopic properties of Cr-doped Ca5(PO4)3F known as Cr:FAP were examined using several different chemical and physical means. Results from analytical titration measurements indicate that chromium is tetravalent in the samples investigated. Based on electron-spin resonance measurements at temperatures as low as 11 K, no trivalent chromium and only a trace of pentavalent chromium (0.5–10 ppm) was detected in the samples used for optical studies. We postulate that Cr4+ is stabilized in the crystal as a result of the small amount of Y2O3 that was added during the crystal growth process and that charge balance is achieved when Y3+ replaces Ca2+ and Cr4+ replaces P5+. Assuming tetravalent chromium, absorption, and emission spectra were interpreted by analyzing phonon sidebands and zero-phonon transitions observed at various temperatures. The observed crystal-field splitting is compared with calculated levels based on a Tanabe–Sugano diagram for quartet and doublet states of Cr4+(3d2) in tetrahedral symmetry. The parametrized Hamiltonian includes the free-ion parameters for Cr4+(3d2) and an initial set of crystal-field parameters obtained from a point-charge lattice-sum calculation where ionic distances were obtained from x-ray crystallographic data. The parametrized Hamiltonian with crystal-field terms in C4 symmetry, when diagonalized within the complete 3d2 configuration, yields calculated Stark levels in reasonable agreement with levels established from the experiment.

Luminescence from Ti2+ ions in LiF crystals

Luminescence of Ti2+: LiF crystals in the wavelength range 650–900 nm excited using laser radiation is reported. The values of 10Dq and the Racah B parameter obtained from the present results indicate that in LiF the 1E, 1T2, and 3T2 energy levels are almost at the “cross-over” point in the Tanabe-Sugano diagram. In consequence photoluminescence from all three energy levels to the ground state is observed. At low temperature (T ∼ 14 K) the emission is mainly due to sharp emission lines with weak vibronic structure due to the 1E, 1T2→3T1 transitions of Ti2+ ions. The 3T2→3T1 broad-band emission is weak at low temperature, becoming stronger at 300 K due to a phonon-assisted tunnelling process, similar to that observed in Cr3+: garnets [1]. The excitation spectrum of these lines is a broad peak at 590 nm due to absorption in the 3T1→3T2 transition.

Partial Quenching of Off-Diagonal Racah Parameters and Diminishing of Diagonal Elements Due to Dynamical Jahn-Teller EffectT1(dN) andT2(dN)×ε

The dynamical Jahn-Teller effect in the case where electronic states T 1 ( d N ) and T 2 ( d N ) ( N =2∼5) couple with doubly degenerate vibrational mode ε in O h symmetry is discussed. The off-diagonal Racah parameters are partially quenched and diagonal ones are diminished by amount of energy gained by Jahn-Teller interaction. As the result, Tanabe-Sugano diagrams are much changed from those without vibronic interaction.

5d transition and 4f rare earth elements in II–VI semiconductors as luminescent centres and probes in diagnostics of implanted layers

Luminescence of implanted Ta, W transition (5d) and Pr, Nd, Er and Tm rare earth (4f) element centres was studied in the II–VI semiconductors CdTe, CdSe, CdS and ZnSe. The radiative transitions were identified in Tanabe-Sugano crystal field theory diagrams as electron transitions between levels with different spins. Impurity-defect complexing was examined in thermal and laser annealing processes.

Co(II)-chloride and -bromide complexes in aqueous solutions up to 5 m Na X and 90°C: Spectrophotometric study and geological implications

Absorption spectra of Co(II)-chloride and bromide complexes have been taken in the UV-visible-NIR region, at temperatures from 25 to 90°C. The octahedral absorption bands have been resolved into components by fitting to Gaussian distribution functions, and the resolved bands have been assigned to ligand-field transitions using Tanabe-Sugano diagrams. The ligand-field-splitting energies, 10 Dq, were obtained for both chloro- and bromo-cobaltous complexes. These data were then used to estimate the average chloro-ligation number at each temperature and the chloride concentrations. At room temperatures and low halide concentrations, essentially only octahedral (6-fold) complexes exist. As the temperature is raised or, especially, as the ligand concentration increases, the complexes undergo a transformation from an octahedral to a tetrahedral (4-fold) configuration. A combination of graphical and numerical methods has been used to determine the stability constants. In the numerical treatment, activity considerations have been incorporated throughout. Based on these stability constants, the thermodynamic data, i.e. enthalpy, entropy and free energy changes, were calculated for all complexation reactions. It was found that the formation of both the first octahedral complex and the sole tetrahedral complex are endothermic. The favourable free energy changes for these reactions are due to gains of entropy inasmuch as they are hard-hard interactions, showing an electrostatic bonding character. The tetrahedral complexes exhibit a greater degree of electrostatic bonding than the first octahedral complex. The other octahedral complexes are extremely weak and do not show typical hard-hard or soft-soft interactions. The octahedral-tetrahedral transformation is strongly favoured by an increase in temperature or halide concentration or both. Thermodynamic calculations suggest that higher halogenated octahedral complexes and, to a lesser extent, Co(H 2O) 6 2+ are selectively converted to the tetrahedral complex, Co X 4 2−. It is possible to factor total dissolved cobalt in a fluid into two terms, a free cobalt term and an enhancement term due to chloride complexation. Investigation of each of the terms shows that under typical, low-temperature hydrothermal conditions ( e.g. during the formation of red-bed type and Mississippi-Valley type deposits), several ppm cobalt can be dissolved in natural fluids, provided that a sufficient source of cobalt is present. For major cobalt mineralization to occur, environmental conditions which produce a high free cobalt term and very high salinities (>5 m at 90°C which give rise to large enhancement factors) are required, in addition to a sufficient source of cobalt.

Spectral studies of Mn2+ in friedelite

Abstract Optical and EPR spectra of Mn 2+ in friedelite are studied both at room and low temperatures. Optical spectrum of sample exhibits four bands in UV-VIS region at room temperature. At low temperature three more bands are observed in the higher energy side. The assignments of the bands are made with the help of Tanabe-Sugano diagram drawn for d 5 configuration with C / B = 5. The EPR spectrum of Mn 2+ in the sample gives a single peak with g = 1.97.

Why Is Ruby Pink? : Years around Tanabe-Sugano Diagrams

Why Is Ruby Pink? : Years around Tanabe-Sugano Diagrams

A widespread error in the d6 Tanabe-Sugano diagram

A widespread error in the d6 Tanabe-Sugano diagram

Renormalized-defect-molecule approach to the theory of substitutional transition-metal ions in semiconductors

A theoretical description of substitutional transition-metal ions in semiconductors is presented. It is based on a defect-molecule approach with renormalized parameters in a manner similar to what has been done for vacancies in silicon. The self-consistent calculation allows conciliation of two apparently opposite behaviors: a quasiatomic spectroscopy classically described by crystal-field theory and the stability of several charge states related to the presence of strongly polarizable bonds. The need for going beyond unrestricted Hartree-Fock theory is emphasized and a method for incorporating the effect of Coulomb correlations in the lower configurations is proposed. Multiplet splitting is then calculated for chromium in GaAs and Si, where the excitation spectrum is shown to resemble that predicted by the Tanabe-Sugano diagrams, but with additional excitations from bonding to antibonding states.

The Syntehesis and Ligand Properties of Potassium Hydrotris- and Tetrakis (5-Nitroindazolyl) Borates

Abstract The synthesis and characterization of two new ligands, potassium hydrotris (5-nitroindazolyl) borate (2) have been achieved. Complexes of (1) with the first row divalent transition metal ions chromium through copper, as well as with palladium and platinum have been prepared, while for (2) complexes with divalent nickel, palladium and tetravalent platinum have been synthesized. All these complexes were formed in 1:2 metal:ligand molar ratio excepting for nickel with ligand (2) which yields a 1:1 complex. These complexes were all non-electrolytes in DMF, the only solvent in which they were soluble. Magnetic susceptibility measurements and ligand field spectral studies indicate an octahedral geometry for all the complexes excepting those of platinum (II) and palladium (II) which have been shown to have a square planar geometry. Some ligand field parameters have been evaluated for a few of these complexes with the help of Tanabe-Sugano diagrams.

Photoluminescence of CdS: V, Cu crystals

In CdS, vanadium on a cadmium site of ${C}_{3\ensuremath{\nu}}$ symmetry represents a center at which various luminescence processes take place at low temperatures. In the present case, copper acceptors also participate. Two emission bands with zero-phonon structures at $\overline{\ensuremath{\nu}}=8681$ ${\mathrm{cm}}^{\ensuremath{-}1}$ and $\overline{\ensuremath{\nu}}=4921$ ${\mathrm{cm}}^{\ensuremath{-}1}$ are ascribed to internal transitions within the ${\mathrm{V}}^{3+}$ ion, i.e., to transitions between levels which are produced in the crystal field by splitting of the degenerate $^{3}F$ term of the free ion: $^{3}T_{1}(F)\ensuremath{\rightarrow}^{3}A_{2}(F)$ and $^{3}T_{2}(F)\ensuremath{\rightarrow}^{3}A_{2}(F)$, respectively. A further broad emission band at $\overline{\ensuremath{\nu}}=14500$ ${\mathrm{cm}}^{\ensuremath{-}1}$ seems to involve a vanadium donor which is part of an associated center. The calculated Tanabe-Sugano diagrams allow an interpretation of the measured excitation spectra and yield fitted Racah and crystal-field parameters. Charge-transfer processes for vanadium and copper ions are discussed in the band model.

Absorption spectra, emission spectra, and magnetic susceptibility of chromium in sodium-β-alumina

Absorption spectra, emission spectra, and magnetic susceptibility from 4.2 to 300°K have been measured for β-alumina doped with 2w o chromium. Chromium-doped β-alumina sintered in air was found to contain only Cr(IV) even though Cr(III) was the oxidation state initially present. Heating air-sintered samples at 1200°C in 10% H 2 90% N 2 for 5 hr reduced the Cr(IV) to Cr(III). The absorption spectra for Cr(IV) and Cr(III) have been fitted to the Tanabe-Sugano diagram and Dq and B were calculated. Results are consistent with the assignment of both Cr(III) and Cr(IV) to octahedral coordination sites in β-alumina. A parallel study of chromium doped α-alumina also showed the existence of Cr(IV) and Cr(III) in that host lattice depending on the firing atmosphere.

Visible and Near IR Spectra of Some Divalent Transition Metal Cupferron Complexes

The visible and near IR spectra of the ammonium salt of cupferron and manganese, cobalt, nickel and copper divalent cupferrate complexes are investigated. New absorption bands observed are given and assigned using the Tanabe-Sugano diagrams. In the absorption spectra of the divalent transition metal cupferrates a characteristic shift in the maxima and minima appears. Solvent effects on this shift were investigated.

Molecular orbital calculations on transition metal complexes. Part VIII. Potential energy curves for some 3d6complexes and their relation to Tanabe–Sugano diagrams

Download options Please wait... Article information DOI https://doi.org/10.1039/DT9740002015 Article type Paper Download Citation J. Chem. Soc., Dalton Trans., 1974, 2015-2020 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Molecular orbital calculations on transition metal complexes. Part VIII. Potential energy curves for some 3d6 complexes and their relation to Tanabe–Sugano diagrams D. W. Clack and W. Smith, J. Chem. Soc., Dalton Trans., 1974, 2015 DOI: 10.1039/DT9740002015 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Dennis W. Clack William Smith

Linear expressions for the first nine electronic transitions of octahedrally coordinated dn ions

Since the Tanabe-Sugano diagrams are linear over wide ranges of Δ, the ligand field strength, it is possible to write the energy of any electronic transition in the form: E = a( ΔBC) + b( BC) + c( BΔ) + d( CΔ) + Eb + fC + gΔ + h where B and C are the Racah parameters. The coefficients a through h were calculated from the original matrices for the lower transitions of d 2 through d 8 ions and a procedure developed to obtain the Δ, B and C values which give the best fit to an experimental spectrum. The coefficients are tabulated for the ranges 5 < Δ < 15, 1 < Δ B < 11, 3 < C B < 6 and 10 < Δ < 35, 10 < Δ B < 60, 4 < C B < 7 . Several spectra are analyseed and the results of the analyses compared with previous treatments.

Curvature of paramagnetic impurity levels in Orgel—Tanabe—Sugano diagrams

There is a new contribution to the curvature of energy levels as a function of the strength of the crystal field. Thus the levels which are flat in the Orgel—Tanabe—Sugano diagrams, in fact, have non-zero curvature and the accidential degeneracies are removed.

Zero-Phonon Transition and Fine Structure in the Phosphorescence of Fe3+ Ions in Ordered and Disordered LiAl5O8

Phosphorescence and excitation spectra have been measured in Fe3+-doped ordered and disordered LiAl5O8. A good fit with the Tanabe-Sugano diagram for a high spin d5 configuration with B=644 cm−1 and C=2960 cm−1 has been obtained. From the calculated 10 Dq value of 8000 cm−1 and a comparison with the excitation spectra of Fe3+ in β-NaAlO2 it has been shown that the spectra are due to Fe3+ ions in tetrahedral interstices. A sharp zero-phonon transition has been observed in the low-temperature phosphorescence and excitation spectra of the ordered phase of LiAl5O8 and its occurrence was found to be correlated with an anomalously small Stokes shift of 500 cm−1. X-ray powder diffraction, phosphorescence, and ESR spectra show that there exist only two phases of LiAl5O8, an ordered and a disordered phase. Evidence is given that the previously postulated metastable phase is a phase with incomplete ordering.

The phosphorescence of Fe 3+ ions in oxide host lattices. Zero-phonon transitions in Fe 3+/LiAl 5O 8

Phosphorescence and excitation spectra have been measured of Fe 3+-doped LiAl 5O 8, β-NaAlO 2, Na-silicate glass and crystalline alumino-silicates. All excitation spectra fit quite well the Tanabe-Sugano diagram for a high spin d 5 configuration. The expected tetrahedral site symmetry of Fe 3+ in the host lattices and the value of the crystalline field parameter are strong evidence for phosphorescence of Fe 3+ ions in tetrahedral oxygen coordination. A sharp zero-phonon transition has been observed in the low temperature phosphorescence and excitation spectra of the ordered phase of LiAl 5O 8.