Probing the interaction of Au,Rh and bimetallic Au–Rh clusters with the TiO2 nanowire and nanotube support

Gold, rhodium and their coadsorbed layers were prepared on titanate nanowires and nanotubes and characterized by X-ray photoelectron spectroscopy (XPS), low energy ion scattering spectroscopy (LEIS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). On titanate nanowire and tube supports the gold 4f_7/2 XP emission appeared after reduction at 83.7 eV and 85.6 eV indicating two different sizes or chemical environments of gold nanoclusters. The titanate nanostructures stabilize the nearly atomically dispersed state of gold (85.6 eV peaks in XPS). Small clusters also developed in rhodium containing samples besides the pure metallic state. Upon CO adsorption on Rh/titanate nanostructures the IR stretching frequencies characteristic of twin form were dominant, whereas bimetallic nanosystems featured a pronounced linear stretching vibration. By performing careful XPS, LEIS and SEM experiments, it was found that, for appropriate Au and Rh coverage, the Au almost completely covers the Rh nanoparticles. CO adsorbed on this surface may induce the surface reconstruction.     

Examining the Chiral Geometry in l04Rh and l06Rh

The criteria for chiral doublet bands based on one particle and one hole coupled to a triaxial rotor have been summarized. Two representative cases in A - 100 odd-odd nuclei, nearly degenerate △I = 1 doublet bands in 104Rh and 106Rh, are checked against these chiral criteria. It is shown that 106Rh possesses better chiral geometry than 104Rh, although the energy near degeneracy is achieved in 104Rh in comparison with the constant energy separation of doublet bands in 106Rh.     

Superconductivity and resistance behaviour of σ-phase alloys: Nb−Rh and Ta−Rh

Superconductivity, structure and electrical resistance behaviour of -phase alloys of Nb–Rh and Ta–Rh are investigated. The Ta–Rh alloys do not become superconducting above 1.2 K. The andH _c2 (0) values of a homogeneous alloy with the composition Nb_65.2Rh_34.8 are 2.95 K, 13.9 kG/K and 23 kG, respectively, whereas for an inhomogeneous alloy with the composition Nb_63.7Rh_36.3 these values are 4.24 K, 5.5 kG/K and 14 kG, respectively. Splat quenching results in a substantial increase in the andH _c2 (0) values of the Rh-rich sample. Annealing (900°C, 100 h) of the Rh-rich sample leads only to small changes in the superconducting properties but a small amount of Nb–Rh solid solution has been formed. The electrical resistance of Nb_65.2Rh_34.8 decreases with decreasing temperature and varies asT ^0.5 between 150 and 240 K and asT between 60 and 140 K. For Ta_70.0Rh_30.0 the temperature coefficient changes to negative values below 170K. values are calculated for Nb–Rh using McMillan's formula. An estimatedT _c value of Ta–Rh is 0.2 K. TheH _c2 (0) values of Nb–Rh are in good agreement with the theoreticalH _c ^2** (0) values.Dedicated to Prof. Dr. W. Buckel on the occasion of his 60th birthday     

非金属N和过渡金属(Mo, Ru, Rh, Pd)掺杂SnO2磁性的第一性原理研究

本文基于第一性原理方法,对非金属元素(N)与过渡金属元素(Mo, Ru, Rh, Pd)掺杂SnO₂的电子结构和磁学性质进行计算分析.结果表明：形成能与过渡金属原子半径密切相关,随着过渡金属原子半径的增加,形成能在降低,其中N-Mo掺杂体系形成能最低,故该体系最容易掺杂形成;能带结构分析表明,由于掺杂体系自旋向上/向下杂质能级的数量和分布均不对称,掺杂体系均有磁性产生;进一步探究态密度可知,体系产生磁性的原因是过渡金属原子和N原子之间产生p-d轨道杂化,最外层电子轨道上的空位及单电子相互耦合所导致.结果表明,由于掺杂原子的引入,SnO₂体系产生磁性,并且掺杂体系呈现亚铁磁性,其中N-Rh掺杂体系的磁性最好,其磁矩为1.88μB,有望成为良好的稀磁半导体材料.     

活性炭担载的Rh—Mo—K合成醇催化剂

采用XRD、EXAFS等技术研究微量贵金属Rh对活性炭担载的Rh-Mo-K合成醇催化剂结构的影响,并关联其催化性能。氧化态Rh-Mo-K／AC样品中Rh与Mo有着较强的相互作用,使得K2Mo2O7向MoO2转化。硫化还原后,Mo主要以MoS2微晶形式存在,其有序结构尺度随Rh含量的增加而减小。经Rh助剂修饰后,催化剂的合成醇催化性能有明显的提高。     

Electronic structure of Rh, Pt, In, and Sn in the mixed-valence systems Eu(Rh1−x Ptx)2 and U(In1−x Snx)3

The electronic structure of Rh, Pt, In, and Sn in the mixed-valence systems Eu(Rh_1−x Pt_x)₂ and U(In_1−x Sn_x)₃ has been studied by the x-ray K line-shift method. It has been found that the occupation of the Rh 4d-shell in Eu(Rh_1−x Pt_x)₂ is higher than that in the metal, and that it grows with decreasing Eu valence (i.e., with increasing 4f-shell occupation). The electronic structure of Pt, In, and Sn in Eu(Rh_1−x Pt_x)₂ and U(In_1−x Sn_x)₃ does not depend on the Eu and U valence and is practically the same as in the metals. These features in the electronic structure of Rh, Pt, In, and Sn in Eu(Rh_1−x Pt_x)₂ and U(In_1−x Sn_x)₃ suggest that the electron released in the f ⁿ → f ⁿ −1+e transitions, rather than transferring to the common conduction band, remains localized at the Eu and U atoms. Fiz. Tverd. Tela (St. Petersburg) 41, 1529–1531 (September 1999)     

Mechanical and Magnetic Properties of Rh and RhH： First-Principles Calculations

Mechanical and magnetic properties of Rh in bcc, fcc structures and RhH in cubic structure are investigated by using first-principles calculations. Theoretical strengths of these structures are given for the first time. The results show that the NaCl-type cubic RhH has a lower bulk modulus and a theoretical strength larger than those of Rh in bcc and fcc structures. A strong magneto-volume effect of a transition from low magnetic moment-low cell volume＇＇ to high magnetic moment-large cell volume＇＇ is also found for both the bcc and fcc Rh structures as well as RhH.     

The level structure of104Rh deduced from the103Rh(n, γ)104Rh reaction

A sensitive, high resolution study of the¹⁰³Rh(n, γ)¹⁰⁴Rh reaction has revealed the presence of 516 transitions in the energy range 3,700 to 7,000 keV. These results have been used to interpret the reaction in terms of a statistical model in which a constant temperature level density is assumed. Previous work which revealed a much simpler level structure is quantitatively explained in terms of resolution and sensitivity. The average reduced radiative width is significantly lower than that reported for nuclides in theA=100 mass region and the width shows an indication of an energy dependence somewhat greater thanE _γ ³ . The neutron separation energy of the reaction is found to be 6,999.0±0.1 keV.     

K~π=5~- rotational bands in neutron-rich Mo,Ru,and Pd nuclei

The collective rotations of the K~π = 5~- configuration in neutron-rich Mo,Ru and Pd isotopes were systematically investigated by the configuration-constrained cranking shell model based on the Skyrme Hartree-Fock method with pairing treated by shell-model diagonalization.The calculations efficiently reproduce the experimental moments of inertia of both the ground-state and side bands.Rotational bands built on two-particle K~π = 5~- configurations have been the subject of intense study.Possible configurations were assigned to the observed 5~- bands in ~(102-106) Mo,~(108-112) Ru and ~(112-114) Pd.We predict the existence of the 5~-bands in ~(108,110) Mo.These results provide deep insights into the structure of neutron-rich nuclei,and provide useful information for future experiments.     

First-principles study of Ar adsorptions on the （111） surfaces of Pd, Pt, Cu, and Rh

In the present paper we give a detailed report on the results of our first-principles investigations of Ar adsorptions at the four high symmetry sites on M （111） （M =Pd, Pt, Cu, and Rh） surfaces. Our studies indicate that the most stable adsorption sites of Ar on Pd （111） and Pt （111） surfaces are found to be the fcc-hollow sites. However, for Ar adsorptions on Cu （111） and Rh （111） surfaces, the most favorable site is the on-top site. The density of states （DOS） is analyzed for Ar adsorption on M （111） surfaces, and it is concluded that the adsorption behavior is dominated by the interaction between 3s, 3p orbits of Ar atoms and the d orbit of the base metal atoms.     

РАДИАЦИОННЫЙ ЗАХВАТ НЕЙТРОНА ЯДРАМИ Sc,Fe, Cu,Mo, Cd и La

, . 20–1000 keV Sc, Fe, Cu, Mo, Cd La.

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The radiative capture of a neutron on Sc, Fe, Cu, Mo, Cd and La nuclei

The energies and intensities of the transitions of a compound nucleus, produced by the capture of a neutron, were measured by means of a single-crystal scintillation spectrometer. The region of energies 20–1000 keV was measured on Sc, Fe, Cu, Mo, Cd and L a nuclei.

     

β-delayed proton decays of 93Pd and 92Rh

β-delayed proton precursors ⁹³Pd and ⁹²Rh were produced by the irradiation of ⁵⁸Ni with a ⁴⁰Ca beam, and identified using proton-gamma coincidence measurements in combination with a helium-jet fast tape transport system. The half-lives of ⁹³Pd and ⁹²Rh were determined to be 1.3(2), 3.0(8) s, respectively. The measured energy spectrum of β-delayed protons and the estimated relative branching ratios to the final states in the daughter nuclei were fitted by a statistic model calculation, and then the ground-state spin and parity of ⁹³Pd were assigned as 9/2^±. Received: 13 April 2001 / Accepted: 22 August 2001     

Perturbed angular correlation and Mössbauer study of the hydrogen distribution near Ru,Rh and Pd in palladium hydride

Mössbauer experiments with the 90 keV resonance of⁹⁹Ru as well as PAC measurements using the 353 and 528 keV - 90 keV cascades in⁹⁹Ru and the 84 keV - 75 keV cascade in¹⁰⁰Rh were combined in a study of the hyperfine interactions produced by the hydrogen distribution near Ru, Rh and Pd atoms in -PdH_x (0.6x1.0). The electric field gradients produced by the non-cubic nearest neighbour hydrogen distribution were found to be very small. This shows that the protons are very strongly shielded and justifies an interpretation of the Mössbauer spectra in terms of isomer shift distributions only. By combining the two methods one thus can obtain a rather detailed picture of the hydrogen distribution near the probe atoms.     

硫化Mo—K—Rh／Al2O3表面物种的XPS研究

假定单一物种的ＸＰＳ峰形为高斯形，对钼，硫和铑峰进行理论拟合，计算各状态物种表面原子浓度，它们的存在形式各为ＭｏＳ２，富硫环境的ＭｏＳ２＋ｘ，未完全硫化还原的Ｍｏ＾６＋和Ｍｏ＾５＋，Ｓ＾６＋，单质Ｓ＾０或Ｓｎ，Ｓ＾２－和富硫环境中的硫钼结构成（Ｓ－Ｓ）＾２－硫链和Ｒｈ＾ｎ＋（ｎ＝３，２，１，０）。分析发现，催化剂加铑使钼易被硫化还原，铑钼作用可以稳定Ｒｈ＾ｎ＋的存在。     

Structural,Magnetic and Optical Properties of Rh2☎ Centres in NaCl Lattices: An Explanation

A method for exploring Jahn—Teller systems in the framework of Density Functional Theory is described in the present work. Using such a method the properties of the Rh^2? centre in NaCl with remote charge compensation are studied. The calculations support the existence of a strong Jahn—Teller effect and account reasonably for the main features of EPR and optical spectra. The onset of charge transfer excitations is calculated to be at about 3.7 eV a fact which concurs with available experimental data. The elongated geometry is found to be about 200cm^?1 more stable than the compressed one in agreement with experiments.     

Thermodynamics and phase diagrams of MoPdRu and related systems

During the irradiation of nuclear fuels up to 10% of the original fissile material (uranium and plutonium) is converted into a wide range of fission products. One particular group of fission-product elements, the transition metals Mo, Tc, Ru, Rh and Pd, are not oxidised at the quite low oxygen potentials existing in the fuels, and are precipitated in the fuel in the form of metallic inclusions. The thermodynamic properties and phase diagram of these alloys are of importance, since the precise composition of these alloys, as a function of radial position can provide important information concerning operating conditions inside a fuel pin. For this reason a thorough reassessment of these systems is under way. This paper reports values of the excess-Gibbs energies of mixing in the MoPd, PdRu and MoRu binary systems, and in the MoPdRu ternary. Calculated sections of the MoPdRu system at selected temperatures are presented.     

High-spin structure of the neutron-rich odd-odd 106, 108 45Rh and 110, 112 47Ag isotopes

The ^{106, 108}Rh and ^{110, 112}Ag nuclei have been produced as fission fragments following the fusion reaction ²⁸Si + ¹⁷⁶Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. The yrast high-spin states of these four odd-odd nuclei, which are observed for the first time, consist of rotational bands in which the odd proton occupies the πg _9/2 subshell and the odd neutron the νh _11/2 subshell. Their behaviour as a function of spin values does not vary with the number of neutrons: as observed in the odd-N neighbouring nuclei, the motion of the odd neutron remains decoupled from the motion of the core, from N = 61 to N = 65. Moreover, the staggering observed in the yrast bands of odd-odd isotopes is strongly reduced as compared to the large values displayed by the rotational bands built on the πg _9/2 subshell in the odd-A Rh and Ag isotopes. The results of particle-rotor calculations indicate that this reduction is related to a change of the core deformation. Received: 1 June 2001 / Accepted: 23 July 2002 / Published online: 10 December 2002 RID="a" ID="a"e-mail: porquet@csnsm.in2p3.fr RID="b" ID="b"Present address: CSNSM IN2P3-CNRS and Université Paris-Sud 91405 Orsay, France. RID="c" ID="c"Present address: NAC, Faure, ZA 7131, South Africa. RID="d" ID="d"Present address: Department of Nuclear Physics, ANU, Canberra ACT 0200, Australia. Communicated by D. Schwalm     

原子吸收法测定心血管中成药中的V,Mo,Ni,Hg

对于心血管疾病这类严重威胁人类的心血管疾病的药物,新品种繁多,要严格控制其主要指标.近50年来,微量元素与心血管疾病的关系,越来越受到人们的重视.文章通过用原子吸收光谱仪对地奥心血康胶囊等心血管中成药中V,Mo,Ni,Hg的测定,知道在治疗心血管的中成药中都含有较丰富的微量元素.通过研究发现V,Mo,Ni对治疗心血管有一定药效.通过该研究,为制订治疗心血管疾病的中成药的微量元素的指纹图谱,提供了有效元素的理论依据.     

Magnetic properties of Yb Mo O and Gd Mo O from rare earth Mössbauer measurements

Using ¹⁷⁰Yb and ¹⁵⁵Gd M?ssbauer measurements down to ∼ 0.03 K, we have examined the semiconducting pyrochlore Yb₂Mo₂O₇ where the Mo intra-sublattice interaction is anti-ferromagnetic and the metallic pyrochlore Gd₂Mo₂O₇ where this interaction is ferromagnetic. Additional information was obtained from susceptibility, magnetisation and ¹⁷²Yb perturbed angular correlation measurements. The microscopic measurements evidence lattice disorder which is important in Yb₂Mo₂O₇ and modest in Gd₂Mo₂O₇. Magnetic irreversibilities occur at 17 K in Yb₂Mo₂O₇ and at 75 K in Gd₂Mo₂O₇ and below these temperatures the rare earths carry magnetic moments which are induced through couplings with the Mo sublattice. In Gd₂Mo₂O₇, we observe the steady state Gd hyperfine populations at 0.027 K are out of thermal equilibrium, indicating that Gd and Mo spin fluctuations persist at very low temperatures. Frustration is thus operative in this essentially isotropic pyrochlore where the dominant Mo intra-sublattice interaction is ferromagnetic. Received 13 January 2003 Published online 4 June 2003 RID="a" ID="a"e-mail: hodges@drecam.saclay.cea.fr