The polarized optical spectra of the ions Ti3+, V3+, Cr3+, Mn3+, Co3+, and Ni3+ in corundum single crystals have been studied at temperatures from 4.2° to 1200°K. A theory of the band strength based on the point‐charge model and p‐d mixing has been developed and applied to the data with results in fair agreement with experiment. The effects of temperature show that the vibrational‐electronic contribution to band strength is quite small at low temperature but may be appreciable at high temperatures. The crystal‐field parameters have been calculated as convergent lattice sums. The observed trigonal‐field parameter has the opposite sign from that calculated by the point‐charge model if the impurity ion is assumed to occupy an Al3+ ion position in the lattice, but has the same sign as calculated for an ion 0.1 A displaced along the c3 axis toward the empty octahedral site. Details of the spectra have been interpreted as showing that the surroundings of an ion are distorted in some electronic states.

Optical spectra of transition-metal ions in corundum

The absorption and emission properties of transition metal (TM)-doped zinc chalcogenides have been investigated to understand their potential application as room-temperature, mid-infrared tunable laser media. Crystals of ZnS, ZnSe, and ZnTe, individually doped with Cr/sup 2+/, Co/sup 2+/, Ni/sup 2+/, or Fe/sup 2+/ have been evaluated. The absorption and emission properties are presented and discussed in terms of the energy levels from which they arise. The absorption spectra of the crystals studied exhibit strong bands between 1.4 and 2.0 /spl mu/m which overlap with the output of strained-layer InGaAs diodes. The room-temperature emission spectra reveal wide-band emissions from 2-3 /spl mu/m for Cr and from 2.8-4.0 /spl mu/m for Co, Cr luminesces strongly at room temperature; Co exhibits significant losses from nonradiative decay at temperatures above 200 K, and Ni and Fe only luminesce at low temperatures, Cr/sup 2+/ is estimated to have the highest quantum yield at room temperature among the media investigated with values of /spl sim/75-100%. Laser demonstrations of Cr:ZnS and Cr:ZnSe have been performed in a laser-pumped laser cavity with a Co:MgF/sub 2/ pump laser. The output of both lasers were determined to peak at wavelengths near 2.35 /spl mu/m, and both lasers demonstrated a maximum slope efficiency of approximately 20%. Based on these initial results, the Cr/sup 2+/ ion is predicted to be a highly favorable laser ion for the mid-IR when doped into the zinc chalcogenides; Co/sup 2+/ may also serve usefully, but laser demonstrations yet remain to be performed.

Transition metal-doped zinc chalcogenides: Spectroscopy and laser demonstration of a new class of gain media

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Electron Paramagnetic Resonance Of Transition Ions

https://iopscience.iop.org/article/10.1149/2.0091601jss/pdf

Spin-Forbidden Transitions in the Spectra of Transition Metal Ions and Nephelauxetic Effect

Laser action in chromium‐doped forsterite (Cr: Mg2SiO4), pumped with a 1.064 μm Nd:YAG laser, was demonstrated for the first time. The free‐running laser emission is centered at 1.221 μm and has a spectral width of 28 nm. An efficiency of 8% has been achieved with an uncoated crystal produced by the laser‐heated‐pedestal growth method. The available evidence suggests that the laser action is due to Cr4+ in tetrahedral sites.

Chromium-doped forsterite laser pumped with 1.06 μm radiation

In this paper, the spin-lattice coupling coefficient G(11) for Mn2+ in the cubic phase of a CsCaCl3 crystal has been calculated from the three microscopic mechanisms which contribute to zero-field splitting. Based on this, the local rotation angle phi(T) for Mn2+ in the tetragonal phase of a CsCaCl3 crystal is estimated from the EPR zero-held splitting b(2)(0)(T). The reasonableness of the local rotation angle is discussed.

Local rotation angle in the structural phase-transition for the mn2+ ion in a cscacl3 crystal

Dual-luminescence-center single-component white-light Sr2V2O7:Eu3+ phosphors for white LEDs

Trivalent europium-doped strontium molybdate red phosphors in white light-emitting diodes: Synthesis, photophysical properties and theoretical calculations

The four optical spectrum bands (or d-d transitions) and six spin Hamiltonian parameters (g factors g(x), g(y), g(z) and hyperfine structure constants A(x), A(y), A(z)) of the rhombic Zr3+ (4d(1)) center in Y3Al5O12 crystal are calculated from the complete diagonalization (of energy matrix) method and the perturbation theory method. The calculated results from both methods are not only close to each other but also in good agreement with the experimental values. It appears that the two microscopic theory methods (which are very close to those used in a 3d(1) system) are effective in the explanations of the optical and electron paramagnetic resonance spectra for a 4d(1) system. From the calculations, the optical spectrum bands are reassigned and the defect structure of the rhombic Zr3+ center in Y3Al5O12 crystal is estimated. (c) 2007 American Institute of Physics.

Optical spectra and spin Hamiltonian parameters for rhombic Zr3+ in Y3Al5O12

The local tetragonal distortions of complexes MF6 formed in Rb2ZnF4 crystals by substitution of Cr3+, Mn2+ and Fe3+ for Zn2+ have been determined from their EPR data. The results are discussed and the intrinsic tetragonal distortion of the host Rb2ZnF4 crystal is assumed.

Wen-Chen Zheng

Papers

Local rotation angle in the structural phase-transition for the mn2+ ion in a cscacl3 crystal

Dual-luminescence-center single-component white-light Sr2V2O7:Eu3+ phosphors for white LEDs

Trivalent europium-doped strontium molybdate red phosphors in white light-emitting diodes: Synthesis, photophysical properties and theoretical calculations

Optical spectra and spin Hamiltonian parameters for rhombic Zr3+ in Y3Al5O12

Local tetragonal distortions of the octahedral environment for substituting Cr3+, Mn2+ and Fe3+ ions in Rb2ZnF4 crystals