Transition Group Ions Research Articles

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.

J-Levels and S-Values in Monatomic Entities and Condensed Matter

Abstract The electron configurations (in spite of being a debatable approximation to the wavefunction) predict correctly the number of levels with given J value, and in the case of reasonably valid Russell-Saunders coupling, their bunching together in (S,L) terms. The similarity with the energy levels in condensed matter attenuates from the 4f to the 5f group, and in d-group compounds (like those outside the transition groups) usually only 5 remains a good quantum number. Recent experimental results, such as the Judd-Ofelt treatment of absorption and fluorescence transition probabilities (of importance for lasers), photoelectron and Auger spectra, antiferromagnetic coupling through anion bridges (allowing excitation of two transition-group ions by the same photon) and arguments for definite spectroscopic and conditional oxidation states, are connected with a general analysis of non-totally symmetric states. It is shown that the less frequent occurrence of positive S values in compounds of elements lighter...

The ESR spectrum of Gd3+/MgO

Electron spin resonance studies have been made at 9.1 GHz on Gd3+/MgO single crystals grown by electrofusion and containing low gadolinium concentrations. A single isotropic line having g=1.992±0.00024 was observed in contrast to the seven line spectrum reported by Abraham. The experimental peak-to-peak linewidth for the −1/2↔+1/2 transition at 293 K was 0.3 mT and was independent of polar angle. This was nearly one hundred times less than the calculated dipolar linewidth and analysis verified that the lineshape was Lorentzian indicating exchange narrowing. The linewidth was independent of temperature from 4.2 to 293 K and the exchange energy derived for a gadolinium concentration of 310 ppm was 15 GHz. A discussion is given of the cubic field splittings of Gd3+ in oxide crystals and a comparison made of the exchange energies of transition group ions in the MgO lattice.

Ferromagnetic resonance of fine grained precipitates in glass: A thumbnail review

Ferromagnetic resonance (FMR) is a sensitive and mature technique for investigating ferro- or ferri-magnetic precipitates in glasses containing transition-group ions or atoms. The FMR spectra of spherical, single-domain particles are amenable to powder pattern analysis, yielding accurate measures of the magnetocrystalline anisotropy fields and g values. Multi-domain effects in metallic iron particles have also been observed and interpreted, and means of identifying unknown precipitated phases have been developed. The present paper serves as an extended abstract of a longer manuscript, in preparation, dealing with the experimental and theoretical foundations of the method [1].

Electron spin resonance in glasses

The present paper reviews a quarter of a century of electron spin resonance (ESR) studies in glasses. Specific subtopics addressed include transition-group ions, radiation-induced defect centers, ferromagnetic precipitates, and photo-induced centers. For brevity, most of the examples in the first three categories are confirmed to the familiar oxide glass systems and only the most concrete conclusions are elaborated. The section treating radiation-induced defects is further abridged in light of several reviews of this topic in the current literature. Even within these limitations of scope, a great diversity of material is summarized. Most of the studies cited provide information concerning the atomic scale structure of the host glasses and several have immediate impact on practical problems ranging from glass technology to geochemistry.

E.S.R. studies of radiation damage and structure in oxide glasses not containing transition group ions: A contemporary overview with illustrations from the alkali borate system

Electron spin resonance (e.s.r.) is a particularly powerful method for identifying and characterizing radiation-induced defects in vitreous materials. This paper reviews the fundamental principles and the present state of the art in applying e.s.r. techniques to achieve these ends in oxide glasses which do not contain transition group ions. A wide variety of generic defect types are discussed in some detail by means of examples from the alkali borate system. These include oxygen-associated trapped hole centers and oxygen-vacancy-associated trapped electron centers, as well as several electron and hole-type centers which are associated with interstitial cations and anions, respectively. Probable analogs in other oxide glasses are pointed out. Special emphasis is placed on the kinds of structural information which can be obtained from these studies.

Electron Paramagnetic Resonance

An Introduction to Transition Group Ions in Crystals J. W. Orton London: Iliffe. 1968 Pp. 240. Price £3 5s. This book is concerned exclusively with paramagnetic resonance from transition metal ions in insulating crystals. The main emphasis is on presenting a simple account of the theory which will be understandable to students with a minimum background of quantum mechanics.

The Physical Principles of Magnetism

The Physical Principles of Magnetism

A generalized effective spin Hamiltonian

A generalized effective spin Hamiltonian HSG describing the electron paramagnetic resonance of transition group ions in a crystal is proposed on the basis of group theory. In this method the spin Hamiltonian is considered strictly by the space-time symmetry. In the first order perturbation, the irreducible spin tensors TLM (L = 0, 1,..., 2S) describe completely the electron paramagnetic resonance of paramagnetic ions with ground state having 2S + 1 energy levels. Some irreducible tensors in several point-group symmetry are presented for convenience of obtaining HSG explicitly. Such a HSG is equivalent to the KS (Koster-Statz) matrix.

A GENERALIZED EFFECTIVE SPIN-HAMILTONIAN

摘要 本文用羣论的方法提出一种推广的等效自旋哈密顿HSG,用它来描述晶体中过渡族离子的顺磁共振性质。HSG严格地考虑了空间和时间的对称性质。在一阶微扰计算的近似上,证明自旋空间的不可约张量组TLM(L=0,1,…,2S)可以完全描述基态有2S+1个能级的顺磁离子的行为。本文给出了某些常见点羣对称度的不可约张量的形式。这样求出的HSG和Koster-Statz矩阵完全等价。 Abstract A generalized effective spin-Hamiltonian HSG describing the EPR of transition group ions in crystal is proposed on the basis of group theory. In this method, HSG is considered strictly by the space-time symmetry. In the first order perturbation, the irreducible spin tensors TLM (L=0,1,…, 2S) describe completely the EPR of paramagnetic ions with ground state having (2S + 1) energy levels. Irreducible tensors in several point-group symmetries are presented for convenience of obtaining HSG explicitly. Such a HSG is equivalent to the Koster-Statz matrix. 作者及机构信息 林福成1, 祝继康2, 黄武汉1 (1)中国科学院; (2)中国科学院,中国科学技术大学1963年应届毕业生 Authors and contacts LIN FU-CHENG1, ZHU JI-KANG2, HUANG WU-HAN1 (1)中国科学院; (2)中国科学院,中国科学技术大学1963年应届毕业生 参考文献 [1] 施引文献

Heats and Entropies of Reaction of Transition Metal Ions with Ethylenediamine

THE heats of formation of complexes between ligands and metal ions are very important to further the ligand field-theory and check its implications. Until now, only the heats of hydration of the first transition group ions have been used for this purpose1 as the thermochemical data on the complexes formed by ligands other than water are very incomplete. The transition metal complexes of ethylenediamine, which have a very nearly octahedral configuration, could also be fruitfully studied in terms of ligand field-theory. Unfortunately only the thermal data on nickel (II), copper (II) and zinc (II) complexes are known2, and so the formation constants have been used instead of the values of enthalpy changes, with the optimistic assumption that the entropy changes remain constant1,3.

Optical Spectra of Hydrated Ions of the Transition Metals

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.

The magnetochemistry of the adsorption of some transition group ions on silica gel

The magnetochemistry of the adsorption of some transition group ions on silica gel