Concepts and methods of ESR dating

Electron spin resonance (ESR) dating is an absolute dating method suitable for the Quaternary which can be applied to a wide range of materials. It is based on determining the natural radiation dose to which a sample has been exposed during its burial period. This paper outlines the basic concepts, and reviews recent studies on the methods and models of ESR dating.

Scope of this paper. This review paper is one of two in this volume providing an overview of recent developments in the field of electron spin resonance (ESR) dating. The paper focuses on studies investigating the fundamental concepts and methods employed in ESR dating, while the companion paper by Rink (this issue) focuses on applications of the method. Previous review articles have been published by Ikeya (1978) and Ikeya (1985), Hennig and Grün (1983), Nambi (1985) and Grün (1989b). Subsequently, papers by Grün (1991), Schwarcz (1994) and Ikeya (1994a); Ikeya (1994b) and Ikeya (1994c) have reviewed specific aspects of the field. There are three books on ESR dating by Ikeya (1986), in Japanese), Grün (1989a)Grün (1989b), in German) and Ikeya (1993), in English) respectively. In view of the coverage of previous reviews of the field, this paper concentrates on research undertaken since 1990.

The first part introduces and outlines the basic ideas of ESR and its application to dating. This is followed by an overview of recent studies concerned with the basic concepts of the field, its methods and models, as independently of specific materials as possible.     

链接琥珀酰亚胺的线性硝酮的合成与ESR研究

该文设计并合成一种新的线性硝酮自由基捕获探针DSC-PBN(N-(4-(((2,5-dioxopy-rrolidin-1-yloxy)-carbonyloxy)methyl)benzylidene)-2-methylpropan-2-N-oxide),并采用UV、MS、1H NMR等一系列手段表征分子结构.进一步通过自由基捕获实验显示,DSC-PBN可与多种活泼自由基反应生成稳定的氮氧自由基加合物,且所得ESR谱图易于解析和分辨.由于DSC-PBN自由基捕获探针链接琥珀酰亚胺基团,可望通过与蛋白质(或多肽)N端的共价键合而应用于生物体系自由基分析.     

Spin concentration in a possible ESR dosimeter: An electron spin echo study on X-irradiated ammonium tartrate

Several single crystals and powder samples of ammonium tartrate, recently proposed as a possible ESR dosimeter, have been X-irradiated with different doses. The total radical concentration has been determined by quantitative cw ESR, by comparison with a standard. The samples have been studied by electron spin echo spectroscopy. The two-pulse echo decay has been obtained and simulated by a single exponential function for different values of the microwave power of the pulses and for different pulse lengths. The dependence of the phase memory time TM on the microwave power has been exploited to get information on the contribution of the instantaneous diffusion to spin dephasing. At room temperature in the range of radical concentrations of 10(18)-10(19) spins/cm3 the instantaneous diffusion is the dominant spin dephasing mechanism. The linear dependence of the instantaneous diffusion on the total concentration of the radicals is in agreement with the theory. From the latter result we conclude that the average radical-radical distance corresponds to a random distribution of the radicals in the matrix. A simple method of measuring the radical concentration by the ESE decays in powder samples of irradiated ammonium tartrate is described.     

Passive magnetic shielded spin polarized electron source with optical electron polarimeter

A new GaAs(100) spin polarized electron source with an optical polarimeter, which is employed in the field of polarized electron and gas atom collision, is presented in detail. The apparatus is passive-magnetic-shielded by a box and a cylinder made of nickel--iron--molybdenum soft magnetic alloy without Helmholtz coil arrangement. And a uniformly distributed residual magnetic field of less than 5×10^-7,T is obtained near the collision area. The spin polarized electron beam is transmitted and focused onto collision point from photocathode by a set of electron optics with more than 25% transmission 95cm distance through an 1mm diameter aperture. Construction and operation of the apparatus, such as vacuum and magnetic shielding system, photocathode, laser optics, electron optics and polarimeter are discussed. The polarization of the spin polarized electron beam is determined to be 30.8\pm3.5% measured with a He optical polarimeter.     

ESR spectroscopy of La2Ga5SiO14:Cr single crystals

The ESR spectrum of La₃Ga₅SiO₁₄ single crystals activated by chromium ions is investigated. It is shown that chromium ions are incorporated into the La₃Ga₅SiO₁₄ crystal lattice in the trivalent state at laoctahedric positions. Orientations of the principal magnetic axes are determined, and parameters of the spin Hamiltonian are estimated. The effect of disorder of the crystal structure of the matrix on line widths and shapes of the ESR spectrum of impurity Cr³⁺ ions is discussed. I. Franko L’vov State University, 50, Dragomilov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 942–946, November–December, 1998.     

Ferromagnetic spin fluctuations in antiferromagnetic Pr1−xCaxMnO3: An ESR study

Electron spin resonance (ESR) measurements have been performed on polycrystalline samples of Pr_1−xCa_xMnO₃ (x=0.4, 0.5) in the temperature range of 100-300 K. The temperature dependence of ESR intensity, g value and linewidth shows the existence of ferromagnetic spin correlations in the paramagnetic state. With decreasing temperature, the ferromagnetic spin correlations switch to antiferromagnetic spin correlations in the charge ordering state and vanish at the antiferromagnetic ordering temperature T_N.     

烯烃聚合催化剂的ESR研究进展

很多烯烃聚合催化剂都含有过渡金属离子. 由于很多过渡金属离子存在未成对电子,ESR可以检测这些含有未成对电子的过渡金属离子,所以ESR检测技术可以被用于聚烯烃催化剂的研究. 该文综述了近年来ESR技术在烯烃聚合催化剂表征领域的研究进展,根据不同过渡金属分类讨论,主要涉及了Ti、Ni、V、Cr等几种常见的过渡金属催化剂的ESR研究.     

紧凑型电子自旋共振(ESR)仪

描述了一种原创的紧凑型电子自旋共振(ESR)仪.该仪器具备高性能、低成本、简单可靠、结构紧凑、开放构架、多功能模块等一系列特点.分析了ESR谱仪的多个微波单位,研发并通过实验验证了自差ESR谱仪的最优双腔结构,并设计了一种可提供高均匀磁场的电、永磁混合磁体.最后介绍了这种新型紧凑型电子自旋共振仪的主要参数和应用.     

MgF2:Mn2+光谱、超精细常数和局部结构的关联

基于电子顺磁共振(EPR)超精细常数A_s确定键长的新方法和半自洽场d轨道理论，对MgF₂:Mn²⁺光谱和EPR超精细常数作出了统一解释.得到室温下MgF₂:Mn²⁺晶体中杂质中心Mn—F的键长为0.2124±0.0010nm. 关键词： 晶体场 电子顺磁共振 光学和磁学性质     

Interaction of two superhigh-frequency fields with the resonance system of electron spins

Within the framework of the concept of a spin temperature in a steady-state regime, the interaction with a resonance medium of two superhigh-frequency fields, one of which is saturating and the other of which is trial, is considered theoretically in the general case without using a high-temperature approximation. The case where the absorption of a resonance medium vanishes at the trial-field frequency is investigated in detail. This occurs with an intensity of the saturating field lower than in the case of a high-temperature approximation. This intensity is estimated in the second and third orders by the parameter ω₀β_z/2, where ω₀ is the resonance frequency of the transition, β_z=ħ/(kT_z), T_z is the Zeeman-subsystem temperature, ħ is the Planck constant, and k is the Boltzmann constant. It is shown that the cooling of the dipole-dipole reservoir is more considerable than in the case of a high-temperature approximation. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 492–495, July–August, 2000.     

Ti：Al2O3晶体的电子自旋共振谱研究

Ｔｉ：Ａｌ２Ｏ３晶体中的顺磁中心Ｔｉ＾３＋由于强烈的晶格自旋耦合而使其电子自旋共振吸收只有在液拟温度附近才能看到，本实验在液氮温度附近记录到由许多强的的吸收峰迭加于Ｔｉ＾３＋宽吸收线所组成的电子自旋共振谱，这些吸吸收峰被认为是Ａｌ２Ｏ３基质中的Ｆｅ＾３＋，Ｍｎ＾２＋，Ｃｒ＾３＋，Ｍｏ＾３＋，Ｆｅ＾２＋，Ｃｏ＾２＋等杂质的共振吸收及Ｔｉ＾２＋３Ａ２ｇ基态的双量子跃迁造成的。     

Anisotropic ESR parameters of Cu(II) complexes in solutions and dynamics of solvent coordination: use of “minimum linewidths”

The “minimum linewidths” seen in the ESR linewidths against temperature plots, the dependence of line widths on the⁶³Cu nuclear magnetic quantum numbers and the Hubbard relation provide sufficient number of equations to determine the anisotropic ESR parameters in the case of axially symmetric Cu(II) complexes even when unresolved hyperfine structures make contributions to linewidths. After testing the method by reanalysing the literature data on Cu(II) bis-acetylacetonate, it has been used to obtain the anisotropic ESR parameters in the case of bis-salicylaldehydate of Cu(II). Linewidth contributions from unresolved hyperfine structures associated with the¹H of coordinating CHCl₃ inferred in these studies, were confirmed by comparing the widths in CHCl₃ and CDCl₃ under ideal conditions. The temperature dependence of this contribution and the estimate of rate constant at room temperature (∼ 10¹⁰ s⁻¹) suggest that the coordinating solvent exchange is diffusion controlled.     

EPR and optical spectra of cupric ions doped in powder strontium maleate tetrahydrate and magnesium Bis (hydrogen maleate) hexahydrate

Abstract

EPR spectra of Cu²⁺ ions doped in a strontium maleate tetrahydrate and magnesium bis (hydrogen maleate) hexahydrate have been studied in X-band at room temperature and at liquid nitrogen temperature. Spin-Hamiltonian parameters have been calculated. Molecular orbital coefficients are obtained by correlating optical absorption data with EPR results.     

Electron spin resonance (ESR) dating and ESR applications in quaternary science and archaeometry

The scope of application of ESR spectroscopy has greatly expanded with the advent of its widespread use in radiation exposure dating around 1980 and its use in retrospective dosimetry since the Chernobyl disaster in 1986. Few fields of study are of such breadth that they span topics as diverse as dating of human origins, volcanic activity, cave deposits and earthquakes, while also providing prognoses for radiation accident victims. Between 1945 and 1975 ESR was mainly used to define the nature of paramagnetic defects in crystalline and amorphous materials, which laid the foundation for its use in applied areas in Quaternary geology, archaeometry and accident dosimetry. This review chronicles the development of the use of ESR in applied science since 1975, with particular emphasis on the state of the art in the period 1987–1997. The first part of the review focuses mainly on the range of applications for datable materials: tooth enamel (Section 2), calcite (Section 3) and quartz (Sections 4–9), while the second part comprises the areas of retrospective dosimetry (Section 10) and new applications (Section 11). The review concludes (Appendix A) with an introduction to the physical basis and assumptions involved in ESR dating, and compilations of valuable reference works for students and workers in this field.     

ESR Induced in CR-39 Plastic as a means of Gamma Ray Dosimetry

The gamma-induced ESR in CR-39 plastic has been studied and the possibility of using it as a gamma-ray dosimeter was investigated. The induced ESR was found to vary linearly with the dose up to 700 krad. The fading of the induced ESR signal at room temperature has been also investigated. The results suggest the possible use of CR-39 plastic for gamma dosimetry in the range 0 … 700 krad.

Es wurde die γ-induzierte ESR-Technik am CR-39 Plast untersucht und ihre Eignung als Gammastrahlen-Dosimeter geprüft. Die induzierte ESR variierte linear bis zu einer Dosis von 700 krad. Das Fading des induzierten ESR-Signals bei Zimmertemperatur wurde ebenfalls untersucht. Die Ergebnisse zeigten, daβ cine Verwendung des CR-39 Plast als Dosimeter für Gammastrahlen im Bereich von 0 … 700 krad möglich ist.     

Site-selective electron nuclear double resonance in the exchange-narrowed regime of the ESR in conducting solids

Electron nuclear magnetic double resonance on conduction electrons reveals the hyperfine interaction hidden by the fast electron spin exchange. We used the Overhauser shift technique to investigate the electron spin density of the conduction band of gallium oxide, beta-Ga(2)O(3). Due to the monoclinic structure, the conduction band of beta-Ga(2)O(3) is anisotropic and it is dominated by contributions from the two nonequivalent Ga sites. The large quadrupole couplings of the two gallium isotopes (69)Ga and (71)Ga (both with I = 3/2) are completely resolved in our double-resonance experiments. This resolved quadrupole interaction allows the determination of the electric field gradients at both gallium sites with high precision and high sensitivity. The resolved quadrupole splitting is the key to the site-selected determination of the hyperfine interaction. The concepts behind these double-resonance techniques are rather general and should be applicable in similar semiconductor systems.     

Study of a set of micrometeorites from Antarctica using magnetic and ESR methods coupled with micro-XRF

A collection of iron-rich micrometeorites from Antarctica have been investigated using electron spin resonance (ESR) and conventional magnetic methods to establish a complete magnetic codification of their specific characteristics. Due to the high selectivity of the ESR, the spectra show that the amount and nature of the magnetic impurities contained in these tiny-sized samples, mainly Ni and Cr ions, significantly modify their ESR responses. This result provides a criterion, the Ni/Cr content (identified by spectroscopy), useful for a faithful classification of this class of extraterrestrial particles with close magnetic properties. We attempt to separate the contribution of the different magnetic ions in the ESR response. This method can be easily extended to other magnetic impurities.     

钙钛矿型锰氧化物(La$lt;sub$gt;0.8$lt;/sub$gt;Eu$lt;sub$gt;0.2$lt;/sub$gt;)$lt;sub$gt;4/3$lt;/sub$gt;Sr$lt;sub$gt;5/3$lt;/sub$gt;Mn$lt;sub$gt;2$lt;/sub$gt;O$lt;sub$gt;7$lt;/sub$gt;的磁性和电性研究

采用传统固相反应法制备钙钛矿型锰氧化物 (La_0.8Eu_0.2)_4/3Sr_5/3Mn₂O₇多晶样品, X-射线衍射分析表明, 样品(La_0.8Eu_0.2)_4/3Sr_5/3Mn₂O₇结构呈现良好的单相. 通过磁化强度随温度的变化曲线(M-T)、不同温度下磁化强度随磁场的变化曲线(M-H)和电子自旋共振谱发现: 在300 K以下, 随着温度的降低, 样品先后经历了二维短程铁磁有序转变 (T_C^2D ≈ 282 K)、三维长程铁磁有序转变(T_C^3D ≈ 259 K)、奈尔转变(T_N ≈ 208K)和电荷有序转变(T_CO ≈ 35 K); 样品 (La_0.8Eu_0.2)_4/3Sr_5/3Mn₂O₇在T_N以下, 主要处于反铁磁态; 在T_C^3D达到370 K时, 样品处于铁磁-顺磁共存态, 在370 K以上时样品进入顺磁态. 此外, 分析电阻率随温度的变化曲线(ρ-T)得到: 样品在金属-绝缘转变温度(T_P ≈ 80 K)附近出现最大磁电阻值, 其位置远离T_C^3D, 表现出非本征磁电阻现象, 其磁电阻值约为61%. 在T_CO以下, 电阻率出现明显增长, 这是由于温度下降使原本在高温部分巡游的e_g电子开始自发局域化增强所致. 通过对 (La_0.8Eu_0.2)_4/3Sr_5/3Mn₂O₇的ρ-T 曲线拟合, 发现样品在高温部分的导电方式基本遵循小极化子的导电方式. 关键词： 磁性 电性 金属-绝缘转变温度 电子自旋共振     

Optical and paramagnetic properties of natural diamonds implanted with hydrogen ions

We used IR spectroscopy and electron spin resonance (ESR) to investigate defect reconstruction processes occurring in diamond crystals due to their implantation with H⁺ ions with energies of 65–350 keV and subsequent isochronous annealing in the temperature range 250–1550°C. We found that most of the hydrogen in diamonds implanted with protons is in an IR-inactive state. Magnetic hysteresis related to radiation defects in diamond is observed for the first time at room temperature using ESR. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 485–490, July–August, 2007.     

Investigating material trends and lattice relaxation effects for understanding electron transfer phenomena in rare-earth-doped optical materials

Rare-earth-doped insulators and semiconductors play an important role in a wide range of modern optical technologies. Knowledge of the relative energies of rare-earth ions’ localized electronic states and the band states of the host crystal is important for understanding the properties of these materials and for determining the potential material performance in specific applications such as lasers, phosphors, and optical signal processing. Current understanding of the systematic variations of electron binding energies in these materials is reviewed with analysis of how lattice relaxation affects the results obtained from different experimental techniques. Detailed examples are presented for rare-earth-doped YAG and LaF₃ material systems. A method for predicting the chemical shift of the 4f electrons of rare-earth impurities from the host crystal’s photoemission spectrum is also demonstrated. Furthermore, a simple model is presented that predicts host-dependent trends in the binding energies of the rare-earth ion states in materials ranging from the elemental metals to the ionic fluorides. By understanding the systematic changes in the relative energies for different states, different ions, and different host materials, insight is gained into electron transfer transitions, valence stability, and luminescence quenching that can accelerate the development of materials for optical applications.