Magnetic order in LaEuSrCuO studied [2pt] by Fe Mössbauer spectroscopy

⁵⁷Fe M?ssbauer effect studies of La_1.65Eu_0.20Sr_0.15CuO₄ doped with 0.5 at% ⁵⁷Fe performed in the temperature region 300 K > T > 4.2 K give an onset temperature for magnetic ordering of K. This temperature practically is the same as that found in Nd doped La_2-xSr_xCuO₄. It indicates that the magnetic ordering temperature in the LTT phase of rare earth (RE) doped La_2-xSr_xCuO₄ is independent of the RE moment. The direction of the ⁵⁷Fe magnetic moment in the magnetically ordered state is within the CuO₂ plane, while it has been found to be parallel to the c-axis in Nd doped La_2-xSr_xCuO₄. Received: 23 June 1998 / Accepted: 14 July 1998     

Evolution of shapes in 59Cu

High-spin states in ⁵⁹Cu were populated using the fusion-evaporation reaction ²⁸Si + ⁴⁰Ca at a beam energy of 122 MeV. The Gammasphere Ge-detector array in conjunction with the 4π charged-particle detector array Microball allowed for the detection of γ-rays in coincidence with evaporated light particles. The resulting extensive high-spin decay scheme of ⁵⁹Cu is presented, which comprises more than 320 γ-ray transitions connecting about 150 excited states. Their spins and parities have been assigned via directional correlations of γ-rays emitted from oriented states. Average quadrupole moments of rotational bands have been determined from the analysis of residual Doppler shifts. Shell model calculations in the fp shell are invoked to study some of the low-spin states, while the experimental characteristics of the rotational bands are analyzed in the configuration-dependent cranked Nilsson-Strutinsky (CNS) approach. Received: 15 February 2002 / Accepted: 23 April 2002     

Optimale Quantisierung

Zusammenfassung. Optimale Quantisierungen oder – damit ?quivalent – minimale Summen von Momenten spielen in mehreren Zweigen der Mathematik und ihrer Anwendungen eine Rolle. Ausgehend von der Fejes Tóth'schen Ungleichung für Summen von Momenten in der euklidischen Ebene und einem zugeh?rigen Stabilit?tssatz, werden gewisse Erweiterungen auf normierte R?ume und riemannsche Mannigfaltigkeiten h?herer Dimension besprochen. Die Ergebnisse werden dann auf Probleme aus folgenden Bereichen angewendet: (i) Datenübertragung, (ii) Wahrscheinlichkeitstheorie, (iii) numerische Integration, (iv) Approximation konvexer K?rper und (v) isoperimetrische Probleme. Eingegangen am 29. Mai 2002 / Angenommen am 8. Juli 2002     

Nuclear forward scattering vs. conventional Mössbauer studies of atomically tailored Eu-based materials

With the decrease in size of devices, rapid characterization of nano-devices is an inevitable necessity. It is shown that Mössbauer spectroscopy using synchrotron radiation from the advanced photon source provides such a tool of investigation. Results are presented and compared for conventional Mössbauer and Nuclear Forward Scattering for ¹⁵¹Eu-doped magnesium sulfide as an example, especially at low concentrations.     

Mössbauer, X-ray diffraction and magnetization studies of Fe–Mn–Al–Nb alloys prepared by high energy ball milling

Fe₆₀Mn₁₀Al₂₀Nb₁₀, (Fe₆₀Mn₁₀Al₃₀)₉₅Nb₅ and (Fe₆₀Mn₁₀Al₃₀)₉₀Nb₁₀ ball milled powdered alloys were investigated using X-ray diffraction, Mössbauer spectrometry, thermomagnetic (TGM) and magnetization measurements. We studied the influence of Nb content and of different milling times on the structural and magnetic properties. Two main features can be concluded: (1) the FeAlMn induces a BCC phase whatever the Nb content is, and (2) as both increasing Nb content and milling time give rise to an highly disordered state in conjunction with a decrease of the ferromagnetic behavior.     

The crystal structure on the set of Mirkovi?-Vilonen polytopes

In an earlier work, we proved that MV polytopes parameterize both Lusztig's canonical basis and the Mirkovi?-Vilonen cycles on the affine Grassmannian. Each of these sets has a crystal structure (due to Kashiwara-Lusztig on the canonical basis side and due to Braverman-Finkelberg-Gaitsgory on the MV cycles side). We show that these two crystal structures agree. As an application, we consider a conjecture of Anderson-Mirkovi? which describes the BFG crystal structure on the level of MV polytopes. We prove their conjecture for sln and give a counterexample for sp₆. Finally we explain how Kashiwara data can be recovered from MV polytopes.     

[Co(2,3-tri)(ibn)Cl][ZnCl4]体系一经式异构体的晶体结构及体系异构体的理论计算研究

用单晶X-射线衍射分析方法解析了[Co(2,3-tri)(ibn)Cl]²⁺(2,3-tri=N-(2-氨基乙基)-1,3-丙二胺,ibn=1,2-二氨基-2-甲基丙烷)体系中一经式异构体(m2-[Co(2,3-tri)(ibn)Cl][ZnCl₄])。该晶体属单斜晶系,空间群P2₁/c,a=11.317(3)?,b=14.931(4)?,c=11.646(3)?,β=1     

用透射积分法研究的穆斯堡尔谱学——一个在聚合二茂铁研究中的应用

本文利用透射积分法，在聚合二茂铁研究中发现，这种方法不但能够得到超精细参数，而且能够得到一般拟合方法得不到的另外两个重要参数—样品的无反冲分数和相应的德拜温度，由此能进一步了解到样品在结合中晶格的质量及化学键的强弱，为穆斯堡尔谱研究提供了一条新的途径。     

二(三苯基膦)水杨酸铜(Ⅰ)乙醇溶剂配合物的晶体结构

0IntroductionThestudyofcopper?complexesisinvestigatedinmanylaboratories.Amongthereasonsforcarryingouttheinvestigationofsuchspeciesaretheirstructuralfeatures犤1犦,theusefulnessofcopper?compoundsinorganicsyntheses犤2犦andthewell-documentedimpor-tanceofcopper?centersattheactivesitesofanumberofprotein犤3犦.Concerningcopper?carboxy-latesafurtherinterestexists,stemmingfromtheiruseinhomogeheouscatalysedhydrogenation犤4犦.Thecopper?bis(triphenylphosphine)cationisasoft,butflexi-bleacceptorionthatcanacc…