New Development of Mossbauer Spectroscopy

穆斯堡尔光谱学在大约40年前被发现，并已成为固体物理领域的有力工具之一。本项目旨在获得穆斯堡尔光谱学的新发展和新成果，并为材料科学如纳米级细粒子科学和锕系元素科学做出贡献。我们在以下的研究项目中发展了穆斯堡尔光谱学。特别要强调的是，近年来同步辐射核共振散射的发展和应用，对于该光谱在材料科学领域的进一步发展是十分重要和必要的。铁氢氧化物的穆斯堡尔光谱研究暴露在自然环境中的钢表面形成的腐蚀产物包括α-FeOOH针铁矿、β-FeOOH阿卡甘石和γ-FeOOH蛭石等氢氧化物。我们对这些氢氧化物进行了穆斯堡尔测量，并确定了这些化合物的相对数量。这些结果已在国际会议上报道并发表。纳米级微细颗粒的穆斯堡尔光谱研究对硼包覆的Fe微细颗粒和SiO_2包覆的FePt微细颗粒进行了穆斯堡尔测量。结果表明，b包覆后的FePt为完美的bcc-Fe，退火后的FePt晶粒为具有四方结构的L1_0有序合金。在SPring8中，利用外差法成功地观测到了同步辐射下的Ta核共振散射。利用SPring8中安装的相同设备，我们成功地首次观测到^<181>Ta核共振光子通过旋转楔形Lucite圆盘的相位调制。通过同步辐射核共振散射的观测，开辟了高能区相位调制、频率调制等超高分辨率光学的新领域。^<237>Np和^<238>U是非常重要的锕系元素。最近在一些锕系化合物中发现了新的磁性和超导性，如NpFeGa_5。在东北大学和日本原子研究机构的合作下，对NpFeGa_5进行了^<57>Fe穆斯堡尔测量，并详细讨论了其磁性能，并在国际会议上发表。少

Mossbauer spectroscopy was discovered about 40 years ago and has been used as one of the powerful tools in the field of solid-state physics. This project aims to get new developments and achievements in this Mossbauer spectroscopy and to contribute in material science like the nanometer-sized fine particle science and also for the actinide science. We have developed Mossbauer spectroscopy in the following research projects. Especially, we have to emphasize that the recent development and application of the nuclear resonant scattering with synchrotron radiation is quite important and essential for the further progress of this spectroscopy in material science.1. Mossbauer spectroscopic study of iron oxyhydroxidesCorrosion products formed on steel surfaces exposed to nature environment consist of oxyhydroxides like α-FeOOH Goethite, β-FeOOH Akaganeit and γ-FeOOH Lepidocrocite. We performed Mossbauer measurements for these oxyhydroxides and determined relative quantities for these compound … More s for the rust on the steel surface. These results obtained was reported and published in international conference.2. Mossbauer spectroscopic study of nano-meter-sized fine particlesMossbauer measurements have been performed for the boron-coated Fe fine particles and SiO_2 coated FePt fine particles. Results obtained clearly show that the B-coated Fe is perfect bcc-Fe and annealed FePt fine particles are tetragonal L1_0 FePt ordered alloy having tetragonal structure.3. Newly developed nuclear resonant scattering with synchrotron radiation^<181>Ta nuclear resonant scattering with synchrotron radiation was successfully observed using heterodyne method in SPring8. Using a same facility installed in SPring8,we have succeeded a first observation of the phase modulation of ^<181>Ta nuclear resonant photons by a rotating wedge shaped Lucite disk. This observation by the nuclear resonant scattering with synchrotron radiation make it possible to open the new field of the ultra-high resolution optics like phase and frequency modulations in high energy region.4. Application of the Mossbauer spectroscopy to the actinide science^<237>Np and ^<238>U are very important actinide elements. Recently novel magnetism and superconductivity have been discovered in some actinide compounds, like NpFeGa_5. Under the collaboration with Tohoku University and Japan Atomic Research Agency, ^<57>Fe Mossbauer measurements have been performed for NpFeGa_5 and discussed its magnetic propertied in detail and published in International conference. Less