同步辐射穆斯堡尔谱学

同步辐射穆斯堡尔谱自从1985年取得突破后, 经历了20多年的长足发展, 已经成为穆斯堡尔谱学的一个成熟的分支。 目前同步辐射穆斯堡尔谱学由两个部分构成: 基于相干核共振散射机制的时域穆斯堡尔谱学和基于非相干非弹性核共振散射机制的X射线谱学。 第三代同步加速器的出现促进了时域穆斯堡尔谱学的发展, 测量得到穆斯堡尔激发态寿命τ期间衰变计数率与时间的关系, 观测到一些有趣的现象。 同步辐射穆斯堡尔谱既能做常规透射谱学研究, 测量各种超精细相互作用及f_LM, δ_SOD等穆斯堡尔参数, 也能利用非弹性核共振散射测量固体的声子谱, 并且也能测出f_LM和 δ_SOD及力常数等, 时域谱和非相干谱的测量精度都高于常规穆斯堡尔谱。 The idea of using synchrotron radiation as a Mössbauer source experienced a breakthrough in 1985, followed by steady development for more than 20 years. Synchrotron Mössbauer spectroscopy consists of two areas. The first one is the so called time domain Mössbauer spectroscopy based on coherent nuclear resonant scattering which permits determination of hyperfine interactions and other Mössbauer parameters such as f_LM and δ_SOD. The other is incoherent nuclear resonant inelastic X ray scattering, which provides vibration information of atoms in a solid, i.e., the phonon density of states. All the experiments have better accuracy than that obtained in conventional Mssbauer spectroscopy.     

Development of On—Line Perturbed Angular Correlation

The on-line time differential perturbed angular correlation technique has been developed for the first time.The quadrupole interaction of ^19F in Cd was measured.     

快重离子辐照效应的穆斯堡尔谱学研究

概述了利用穆斯堡尔效应开展的固体材料快重离子辐照效应研究的部分结果 ,并对建立在兰州重离子加速器 (HIRFL)上的在束穆斯堡尔谱学研究装置及其应用作了简要的介绍.Mssbauer spectroscopy study of irradiation effects induced by swift heavy ions in solid materials were briefly presented.Amorphization phenomenon of yttrium iron garnet irradiated by 1 GeV Ar ions has been investigated. For the first time, the nearly complete amorphous state was observed. Stainless steel 316L samples were irradiated with 54 MeV C ions and phase transformation of the samples was observed. HT 9 ferrite steel was irradiated with 510 MeV C ions. Its phase...     

Moessbauer Investigation of the Ferromagnetic Coupling in Copper-Iron Polycyanides

One of the Prussian blue analogs, molecular magnet Cu3^Ⅲ [Fe^Ⅲ (CN)6]2.11.6H2 O, was investigated by Moessbauer spectroscopy. It was found that transition temperature was around Tc = 18.5 K from paramagnetic phase to ferromagnetic phase. The β value of the critical exponent is around 0.338 at magnetic ordering temperature.Therefore, the ferromagnetic coupling interaction of Cu-Fe cyanide could be clearly explained by spin wave theory.     

Rhodium Moessbauer Effect Generated by Bremsstrahlung Excitation

A method for effectively generating long-lived Moessbauer photons and methods for proving the associated ;Moessbauer effects are reported. For the first time, we observed resonant propagation and resonant absorption of 40-keV Moessbauer photons emitted from ^103Rh through （γ, γ′） process excited by bremsstrahlung. This is a new efficient way to generate long-lived isomer （〉 1ms） for Moessbauer spectroscopy with sufficient brilliance. An abnormally large ratio of resonant absorption between horizontal and vertical directions indicates horizontal trapping- of Moessbauer photons and anisotropic Mbssbauer emission, which can be attributed to gravitational effect on the ^103Rh Moessbauer isomer with extremely narrow 10^-19eV linewidth.     

穆斯堡尔谱学研究进展

本文评述1988～90年穆斯堡尔谱学的进展.穆斯堡尔效应的应用继续扩展到几乎所有的科学领域.论文主要涉及基础研究,有些涉及工业应用和材料研究.论文年发表数持续快速增长.在这期间由每年发表1500篇增至1800篇.国际会议频繁,并且大量被评述.它们总的表明,这个研究领域是非常活跃的. The developments and achievements in M(?)ssbauer spectroscopy during recent 3 years are reviewed.The use of the M(?)ssbauer effect is still increasing and expanding to all subjects of sciences.Most of the papers concern with fundamental research,some refer to in- dustrial applications and many are about material research.The growth in the M(?)ssbauer lit- erature continues rapidly.During this period of time the number of M(?)ssbauer publications increased from ...     

Transport Efficiency of Gas-jet Tape Transport System

The Gas-jet Tape Transport System (GTTS) was used in several on-line experiments. The transport efficiency of GTTS was studied with three different inorganic salts, PbI2, PbC12 and NaC1, by using a ^252 Cf source. The fission fragments of ^252Cf were transported and collected by the GTTS before measurement. Nitrogen gas was used as a substitute of cxpensive Helium gas, in consideration of longer stopping range of fragments. The fragments were also directly collected on Aluminum foils with thickness of 50μm for original yield measurement.     

Measurement of the total reaction cross section for the mirror nuclei ^12N and ^12B

The mirror nuclei ^12N and ^12B are separated by the Radioactive Ion Beam Line in Lanzhou （RIBLL） at HIRFL from the breakup of 78.6 MeV/u 14N on a Be target. The total reaction cross-sections of ^12N at 34.9 MeV/u and ^12B at 54.4 MeV/u on a Si target have been measured by using the transmission method. Assuming ^12N consists of a ^11C core plus one halo proton, the excitation function of ^12N and ^12B on a Si target and a C target were calculated with the Glanber model. It can fit the experimental data very well. The characteristic halo structure for ^12N was found with a large diffusion of the protons density distribution.     

Excitation Function Measurement in Reaction of ^19F＋^27Al

The measurement of excitation functions for the strongly dissipative collision with the reaction system of ^19F ^27Al has been carried out at the China Institute of Atoraic Energy, Beijing. The ^19F^8 beam was extracted from the HI-13 tandem accelerator. The beam incident energies were varied from 110 to 118.75 MeV in steps of 250 keV. The self-supporting ^27A1 target foil with the thickness of 60μg/cm^2 was used. The detector arrangement is shown in Fig.1.     

纪念穆斯堡尔效应发现40周年

文章论述了穆斯堡尔效应的发现和穆斯堡尔谱学的基本原理，并对穆斯堡尔谱学在材料科学、生物医学、考古学和地质矿物学中的应用进行了讨论     

Conversion Electron Moessbauer Spectroscopie Studies on Ion Implanted Iron Layers

Conversion electron Moessbauer spectroscopy (CEMS) is a method very suitable for the study of ion implanted iron. It is demonstrated on nitrogen and phosphorus implanted iron layers. Using this technique not the 14.4-keV-gamma-rays as in the case of the conventional Moessbauer transmission experiments but the conversion and Auger electrons are detected. These electrons have a maximum energy of 7.3 keV. The Moessbauer signal can be obtained from a surface layer of about 300 nm. But the main fraction of the signal, namely 65%, comes from the first 50 nm. This range is just interesting for ion implantation. Depending on the test conditions different iron nitrides are formed by the nitrogen implantation and the phosphorus implantation can result in both amorphization and compound formation in the implanted layer.     

The possibility of the application of the Mössbauer effect to the study of radio-frequency magnetization processes

The Moessbauer effect methodology is proved to be applicable for investigating the RF magnetization of magnetic materials. The characteristic trasformation of Moessbauer spectra is reported for various magnetization mechanisms.     

The splitting of hyperfine lines of57Fe nuclei in RF magnetic field

It is shown experimentally, that for Moessbauer nuclei affected by the radio-frequency (RF) magnetic field of sufficient intensity at frequencies corresponding to NMR, splitting of Zeeman sublevels of nuclei and changes in Moessbauer spectral structure occurs. Depending on the frequency of alternating field each spectral line is splitinto (2·Ig,e +1) comporients, Ig,e-being the nuclear spin of ground and excited state, respectively. The intensity of RF components and the energy gap between them are extremely sensitive to the frequency and the intensity of the RF magnetic field.     

Determination of amplification factor and intensity of alternating magnetic field on a nucleus by Mössbauer spectroscopy

The Moessbauer effect 15 reported to be useful in precision measurements of alternating magnetic field intensity at a nucleus and in determining the PF field gain factor in magnetically ordered material’s. The scope of this method is recognized to manifest itself in a most clear way on pumping of the nuclear spin system by the The problem of Moessbauer lines shape is considered theoretically for the case of nuclei excited by linearpolarized RF field.     

Structural and magnetic properties of Co1-xZnxFe2O4 nanoparticles

Co1-xZnxFe2O4 nanoparticles, prepared by the polyvinyl alcohol sol-gel method, have been investigated by x-ray diffraction and MSssbauer spectroscopy. These results are compared with those for the bulk material. The lattice parameters of CoZn ferrite nanoparticles are larger than those of the bulk material. Thermal scanning of MSssbauer measurement shows that the transition temperatures for nanoparticles are higher than those of the bulk material except for the sample CoFe2O4.     

Die Spaltung schwerer Kerne

This article is concerned with some unusual experiments to demonstrate the wide variety and the great potential of resonance outside the appreciation what is commonly expressed by the Moessbauer effect. It contains contributions of typical interbranch research.     

Organotin anions in solution and in the solid state

Moessbauer data have been obtained for a series of organotin anions. The spectra of these anions in solution show the presence of two species, a singlet in the tin(IV) region and a doublet in the tin(II) region. The crystal structure of triphenyltin anion with potassium in 18-crown-6 as the cation has been determined. The Moessbauer spectrum of this sample is a doublet in the tin(II) region.     

Mixed valency and first order phase transition in EuPdAs

The intermetallic alloy EuPdAs exhibits a first order phase transition at 180 K. The transition is seen by anomalies in lattice parameters, susceptibility, resistivity, Moessbauer effect and X-ray absorption. It is accompanied by an increase of the Eu valence from 2.15 to 2.40 between 300 K and 4 K. The nature of the non-integral valence and the phase transition are discussed.     

金刚石压腔高温高压原位谱学研究的评述

金刚石压腔 (DAC)已经可以达到 5 5 0 GPa的压力和 6 0 0 0 K的温度 ,其高温高压谱学原位测量已经成为现代科学的一种重要的手段和方法。目前利用 DAC可以进行光谱学 (拉曼光谱、红外光谱、荧光光谱 )、衍射 (X射线衍射和 XAFS)、布里渊散射、核磁共振 (NMR)以及穆斯堡尔谱的高温高压原位研究。设计用于各种不同需要的便宜的压腔、合适的谱学测量方法以及压力内标物质是进一步拓宽 DAC应用的发展方向。     

Study of ageing effects of a low-interstitial 18Cr-2Mo ferritic steel

The phase transformations which occur in the 18Cr-2Mo ferritic steel by annealing in the temperature range 603–1093 K have been studied using Moessbauer spectroscopy and X-ray diffraction. It is found that the 748 embrittlement is to be ascribed to Cr redistribution and/or to the formation of an intermetallic R-type phase. Precipitation of an h.c.p. Laves phase Fe (Mo,Nb) of MgZn₂-type takes up at about 850 K and Nb to Mo substitution goes on by increasing the annealing temperature.