Neutron in-beam Mossbauer

A Hungarian group [68] has recently commenced a neutron in-beam Mossbauer study using a cold neutron source (flux of 10 n cm s ) and a guide system at the Budapest Research Reactor. 

IN-BEAM MOSSBAUER SPECTROSCOPY USING A RADIOISOTOPE BEAM AND A NEUTRON CAPTURE REACTION... 

In-beam Mossbauer spectroscopy (IBMS) involves online measurement of Mossbauer -Y-radiation emitted from excited atoms produced by nuclear reactions, Coulomb excitation, and radioisotope (Rl) implantation. It provides useful information on local atomic and electronic configurations (i.e., site distributions, dynamic diffusion processes, and unusual chemical states) of extremely dilute atoms during the lifetime of the excited Mossbauer state. Physical and chemical transformations that occur in nonequilibrium and metastable states immediately after nuclear reactions and implantation can be observed in suitable materials. This chapter introduces past and current experimental techniques of in-beam Mossbauer spectroscopy and reviews some recent topics using Mn (T /2 = 85s) nuclei at RIKEN Rl Beam Factory (RIBF) and thermal neutron capture reaction. 

The remainder of this chapter is organized as follows. The next section describes some experimental and application investigations of in-beam Mossbauer spectroscopy using a Mn beam at the RIKEN RIBF. The system used for detecting Mossbauer 7-radiation in in-beam experiments is important. Nagatomo et al. [32] have recently developed a highly sensitive resonance counter based on parallel-plate avalanche and plastic scintillation counters. A new anticoincidence detection system is introduced. Finally, the experimental setup for online Mossbauer spectroscopy using the thermal neutron capture reaction, Fe (n, 7) Fe, and the results obtained are presented in the subsequent section. 

Neutron capture in-beam Mossbauer spectrum of FeS2 (pyrite type) at room temperature. Measurement time was 70 h. (Reproduced from Ref. 66 with permission of Springer.)... 

In Chapters I and 2, an introduction is made to the synchrotron Mossbauer spectroscopy with examples. Examples include the/ns/tu Mossbauer spectroscopy with synchrotron radiation on thin films and the study of deep-earth minerals. Investigations of in-beam Mossbauer spectroscopy using a Mn beam at the RIKEN RIBF is presented in Chapter 3. This chapter demonstrates innovative experimental setup for online Mossbauer spectroscopy using the thermal neutron capture reaction, Fe (n, y) Fe. The Mossbauer spectroscopy of radionuclides is described in Chapters 4-7. Chapter 4 gives full description of the latest analysis results of lanthanides Eu and Gd) Mossbauer structure and powder X-ray diffraction (XRD) lattice parameter (oq) data of defect fluorite (DF) oxides with the new defect crystal chemistry (DCC) Oq model. Chapter 5 reviews the Np Mossbauer and magnetic study of neptunyl(+l) complexes, while Chapter 6 describes the Mossbauer spectroscopy of organic complexes of europium and dysprosium. Mossbauer spectroscopy is presented in Chapter 7. There are three chapters on spin-state switching/spin-crossover phenomena (Chapter 8-10). Examples in these chapters are mainly on iron compounds, such as iron(lll) porphyrins. The use of Mossbauer spectroscopy of physical properties of Sn(ll) is discussed in Chapter I I. 

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