ARelativisticDensityFunctionalStudyofEarlyTransitionMetalGroupⅢB－VBDimers￣＊

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Anion photoelectron spectroscopy of germanium and tin clusters containing a transition- or lanthanide-metal atom; MGe(n)- (n = 8-20) and MSn(n)- (n = 15-17) (M = Sc-V, Y-Nb, and Lu-Ta)

The electronic properties of germanium and tin clusters containing a transition- or lanthanide-metal atom from group 3, 4, or 5, MGe(n) (M = Sc, Ti, V, Y, Zr, Nb, Lu, Hf, and Ta) and MSn(n) (M = Sc, Ti, Y. Zr, and Hf), were investigated by anion photoelectron spectroscopy at 213 nm. In the case of the group 3 elements Sc, Y, and Lu, the threshold energy of electron detachment of MGe(n)(-) exhibits local maxima at n = 10 and 16, while in the case of the group 4 elements Ti, Zr, and Hf, it exhibits a local minimum only at n = 16, associated with the presence of a small bump in the spectrum. A similar behavior is observed for MSn(n)(-) around n = 16, and these electronic characteristics of MGe(n) and MSn(n) are closely related to those of MSi(n). Compared to MSi(n), however, the larger cavity size of a Ge(n) cage allows metal atom encapsulation at a smaller size n. A cooperative effect between the electronic and geometric structures of clusters with a large cavity of Ge(16) or Sn(16) is discussed together with the results of experiments that probe their geometric stability via their reactivity to H(2)O adsorption.     

Combined pseudopotential and density functional study of Bis-eta6-benzene d and f element complexes

The electronic and molecular structures of selected zerovalent d and f metal bis-eta6-benzene sandwich complexes M(C6H6)2 (M = Sc, Ti, V, Cr, Y, Zr, Nb, Mo, La, Ce, Gd, Lu, Hf, Ta, Nb, Th) were investigated at the scalar-relativistic level using a combination of energy-consistent ab initio pseudopotentials and gradient-corrected density functionals. The results are compared to previous pseudopotential coupled-cluster and all-electron density functional results based on the zero-order regular approximate Hamiltonian of Chang, Pelissier, and Durand as well as to experimental data.     

Homonuclear transition-metal trimers

Density-functional theory has been used to determine the ground-state geometries and electronic states for homonuclear transition-metal trimers constrained to equilateral triangle geometries. This represents the first application of consistent theoretical methods to all of the ten 3d block transition-metal trimers, from scandium to zinc. A search of the potential surfaces yields the following electronic ground states and bond lengths: Sc3(2A1',2.83 A), Ti3(7E',2.32 A), V3(2E",2.06 A), Cr3(17E',2.92 A), Mn3(16A2',2.73 A), Fe3(11E",2.24 A), Co3(6E",2.18 A), Ni3(3A2",2.23 A), Cu3(2E',2.37 A), and Zn3(1A1',2.93 A). Vibrational frequencies, several low-lying electronic states, and trends in bond lengths and atomization energies are discussed. The predicted dissociation energies DeltaE(M3-->M2+M) are 49.4 kcal mol(-1)(Sc3), 64.3 kcal mol(-1)(Ti3), 60.7 kcal mol(-1)(V3), 11.5 kcal mol(-1)(Cr3), 32.4 kcal mol(-1)(Mn3), 61.5 kcal mol(-1)(Fe3), 78.0 kcal mol(-1)(Co3), 86.1 kcal mol(-1)(Ni3), 26.8 kcal mol(-1)(Cu3), and 4.5 kcal mol(-1)(Zn3).     

Structural,mechanical and electronic properties of transition metal hydrides MH2 (M = Ti,Zr, Hf,Sc, Y,La, V and Cr)

First-principles calculations have been carried out to investigate the structural, mechanic and electronic of transition metal hydrides MH₂ (M = Ti, Zr, Hf, Sc, Y, La, V and Cr). It is found that TiH₂ is mechanically unstable because of a negative C₄₄ = −21.31 GPa and C₁₁–C₁₂ < 0, the same behavior can be found in MH₂ (M = Zr, Hf, and Y) compounds. Also there is a strong interaction between M (Ti, Zr, Hf, Sc, Y, La, V and Cr) and H. On the other hand, the H–H bond orders are always negative or nil reason of brittleness.     

Radioanalytical methods for the non-destructive analysis of lunar samples

The elemental compositions of Apollo 11 and Apollo 12 lunar soil samples 10084,141 and 12070,83 and Apollo 12 rock fragment 12063,73 were determined by non-destructive radioanalytical methods. Main mineral fractions and glasses separated from these samples were analyzed as well. Instrumental neutron activation analysis (INAA) was used to determine Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Cs, Ba La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, Lu, Hf, Ta, W, Ir, Au, Th and U. A method of delayed neutron counting was used for the determination of uranium, and non-dispersive radioisotopic X-ray fluorescence analysis was applied to the determination of Ti, Fe, Sr, Y and Zr.     

NAA and ICP analysis of obsidian from Central Europe and the Aegean: Source characterisation and provenance determination

INAA and ICPES are compared for their discriminative power in obsidian source characterisation. Geological samples from the Aegean and Carpathian sources were analysed for Na, Sc, Fe, Co, Rb, Sb, Cs, Ba, La, Ce, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Th, U by INAA and for B, Na, Mg, Al, K, Ca, Sc, Ti, Mn, Fe, Zn, Y, Yr, Cs, Ba, La, Ce, Sm, Eu, Gd, Tb, Yb, Lu, Hf by two ICPES procedures. It is shown that all techniques work successfully, however, INAA is more efficient in the chemical discrimination of neighbouring sources.     

H_3~+体系基态和电子激发态的价键方法研究

本文应用价键理论的键表酉群方法,讨论H_3~+体系的基态及其几个低激发态,研究了该体系处于激发态时价键结构的变化,得到H_3~+体系的基态为等边三角形,第一激发态为直线型,第二、三激发态为等腰三角形,且基本简并.     

Elemental content in ground and soluble/instant coffee

The concentration of thirty-four elements in twelve coffee brands has been measured using instrumental neutron activation analysis. The samples investigated included four brands of commercially available ground coffee and eight brands of soluble/instant coffee. The elements measured were Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Gd, Hf, K, La, Lu, Mg, Mn, Na, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Ti, Tm, U, V, Yb and Zn. Twenty four elements were found to be below the detection limit in one or more samples. These elements were Ce, Cr, Fe, V, As, Eu, Ba, Dy, Gd, Hf, La, Lu, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Ti, Yb, Tm, and U.     

Imaging of the structure of the argon and neon dimer, trimer, and tetramer

We Coulomb explode argon and neon dimers, trimers, and tetramers by multiple ionization in an ultrashort 800 nm laser pulse. By measuring all momentum vectors of the singly charged ions in coincidence, we determine the ground state nuclear wave function of the dimer, trimer, and tetramer. Furthermore we retrieve the bond angles of the trimer in position space by applying a classical numerical simulation. For the argon and neon trimer, we find a structure close to the equilateral triangle. The width of the distribution around the equilateral triangle is considerably wider for neon than for argon.     

Separation of nickel from other elements by cation-exchange chromatography in dimethylglyoxime/hydrochloric acid/acetone media

Nickel can be separated from Zn, Co, Cu(II), Mn(II), Fe(III), U(VI) and other elements which readily form chloro complex ions, by eluting them with 0.5 M HCl/93% acetone from AG50W-X4 resin. Nickel is then eluted selectivity with 0.5 M HCl/95% acetone containing 0.1 M dimethylglyoxime, while the alkali and alkaline-earth elements, Al, Ti(IV), Sc, Y, La, lanthanides, Zr, Hf and Th are still retained. Separations are sharp and quantitative.     

Major,minor and trace element mass fractions determined using ED-XRF,WD-XRF and INAA for five certified clay reference materials: NCS DC 60102–60105; NCS DC 61101 (GBW 03101A, 03102A, 03103, and 03115)

Major, minor and trace element mass fractions were determined using wavelength dispersive and energy dispersive X-ray fluorescence and instrumental neutron activation analysis for five clay certified reference materials (NCS DC 60102–60105, 61101) distributed by the National Research Center for Certified Reference Materials in China. We report mass fractions for 10 major and the following 29 minor and trace elements: As, Ba, Ce, Co, Cr, Cs, Cu, Eu, Hf, La, Lu, Nb, Nd, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, U, V, Y, Yb, Zn, and Zr.     

1-dicarboxymethylaminomethyl-2-hydroxy-3-naphthoic acid as a sensitive and selective fluorimetric reagent for beryllium,and for lanthanum and lutetium in presence of the other lanthanides

1-Dicarboxymethylaminomethyl-2-hydroxy-3-naphthoic acid (DHNA) forms fluorescent complexes with Al, Be, Ga, Hf, In, La, Lu, Mg, Sc, Th, Y, and Zr. The Be, La and Lu complexes have a metal : ligand ratio of 1:1. The beryllium complex shows maximal fluorescence at pH 6.8 with excitation-fluorescence maxima at 360 and 450 nm; linear calibration curves are obtained in the range 0.09–1.8 μg Be. In the presence of the calcium-EDTA complex, of 25 cations studied, only > 100-fold molar ratios of aluminium and > 10-fold molar ratios of magnesium and scandium caused interference in the determination of 0.1 μ mole of beryllium. Amongst 15 anions, > 100-fold molar ratios of phosphate, > 50-fold molar ratios of arsenate or oxalate and > 10-fold molar ratios of citrate, fluoride and tartrate caused low results. Lanthanum and lutetium can be determined at PH 10 and 370/460 nm in the range 7–28 μg even in the presence of a 3-fold molar ratio of the other lantlianides without interference.     

Grundlagen zur halbquantitativen Bestimmung der Elemente in der Laser-Mikrospektralanalyse. II

Zusammenfassung Für die folgenden Elemente wurden die Grundlagen für eine halbquantitative Konzentrationsbestimmung mit Hilfe des Laser-Mikrospektralanalysators ermittelt, und zwar differenziert für Untersuchungen an oxidischen und an metallischen(^*) Materialien: Li, B, Na, P, K, Ca, Sc, Ti, V^*, Ge, As^*, Sr, Y, Zr^*, Nb, Pd, Te, Ba, La, Ce, Nd, Eu, Gd, Er, Yb, Lu, Hf, Ta, W^*, Ir, Pt^*, Au, Hg^*.

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Principles of semi-quantitative determination of elements by laser-microspectroscopy. II

The principles for the semi-quantitative determination of the following elements by laser-microspectroscopy have been investigated separately for oxidic and metallic(^*) materials: Li, B, Na, P, K, Ca, Sc, Ti, V^*, Ge, As^*, Sr, Y, Zr^*, Nb, Pd, Te, Ba, La, Ce, Nd, Eu, Gd, Er, Yb, Lu, Hf, Ta, W^*, Ir, Pt^*, Au, Hg^*.

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Teil I: H. Schorth [3].     

Determination of elements in SRM soil 2709a by neutron activation analysis

A combination of instrumental neutron activation analysis (INAA) and prompt gamma-ray activation analysis (PGAA) was used to value assign 35 elements in SRM soil 2709a (San Joaquin Soil). INAA with counting of short-lived radioisotopes was used for determination of Al, Au, Ca, Dy, K, Mg, Mn, Na, Ti, and V. Elements determined by INAA with counting of intermediate and long-lived radioisotopes included As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Nd, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Yb, Zn, and Zr. Thermal neutron PGAA was used for the determination of H, B, Si, K, Ti, Mn, Fe, Cd and Gd. Expanded uncertainties were determined for all values reported.     

Comprehensive interpretation of a substitution effect on an order-disorder phase transition in A(1-x)MxW2O(8-y) (A = Zr, Hf; M = trivalent cations) and other ZrW2O8-based solid solutions

Hf(1-x)Lu(x)W(2)O(8-y) solid solutions up to x = 0.04, based on a negative thermal expansion material HfW(2)O(8), were synthesized by a solid state reaction method. X-ray diffraction experiments of these solid solutions from 90 to 560 K indicated thermal contraction with increasing temperature. Temperatures of order-disorder phase transition (T(trs)) associated with the orientation of WO(4) tetrahedra were determined from disappearance of a characteristic diffraction peak (310). The T(trs) of the solid solutions drastically decreased with increasing Lu content. Saturated order parameters (eta(s)) associated with the orientational order of the WO(4) pairs were estimated from the characteristic diffraction peak at sufficient low temperature. These behaviors of Hf(1-x)Lu(x)W(2)O(8-y) are consistent with those of Zr(1-x)M(x)W(2)O(8-y) (M = Sc, Y, In, Lu). The drastic suppression of T(trs) in Hf(1-x)Lu(x)W(2)O(8-y) can be interpreted in the framework of a model proposed for Zr(1-x)M(x)W(2)O(8-y), which states the existence of a local nanoregion including the WO(4) pairs having the frozen-in orientational disorder. To understand the substitution effect on the order-disorder phase transition comprehensively, classification based on the saturated order parameter eta(s) of the phase transition of AW(2)O(8) (A = Hf, Zr)-based solid solutions was carried out and discussed.     

Electronic and geometric stabilities of clusters with transition metal encapsulated by silicon

Silicon clusters mixed with a transition metal atom, MSin, were generated by a double-laser vaporization method, and the electronic and geometric stabilities for the resulting clusters with transition metal encapsulated by silicon were examined experimentally. By means of a systematic doping with transition metal atoms of groups 3, 4, and 5 (M = Sc, Y, Lu, Ti, Zr, Hf, V, Nb, and Ta), followed by changes of charge states, we explored the use of an electronic closing of a silicon caged cluster and variations in its cavity size to facilitate metal-atom encapsulation. Results obtained by mass spectrometry, anion photoelectron spectroscopy, and adsorption reactivity toward H2O show that the neutral cluster doped with a group 4 atom features an electronic and a geometric closing at n = 16. The MSi(16) cluster with a group 4 atom undergoes an electronic change in (i) the number of valence electrons when the metal atom is substituted by the neighboring metals with a group 3 or 5 atom and in (ii) atomic radii with the substitution of the same group elements of Zr and Hf. The reactivity of a halogen atom with the MSi(16) clusters reveals that VSi(16)F forms a superatom complex with ionic bonding.     

Liquid anion-exchange extraction and separation of yttrium,neodymium and samarium

Yttrium, neodymium and samarium are extracted from sodium succinate solution with tri-n-octylamine in benzene and determined spectrophotometrically. Procedures for the separation of microgram amounts of Y, Nd and Sm from La, Sc, Dy, Hf, Zr, Ce(IV), Th and U(VI) are described.     

Hyperfine splittings in spin-frustrated trinuclear Cu(3) clusters

The hyperfine structures of the EPR spectra of the spin-frustrated and distorted Cu(II) trimers were calculated in the spin-coupling model. The correlations between the hyperfine structures of the EPR spectra and geometry of the Cu(3) clusters (equilateral, isosceles, and scalene triangles) were found. For the EPR spectrum of the spin-frustrated ground state 2(S = 1/2) of an equilateral triangle Cu(3) cluster (J(12) = J(13) = J(23) = J), the calculated hyperfine structure represents the complicated spectrum of the 24 hyperfine lines, of total length 5a, where a is the hyperfine constant of the mononuclear Cu center. For an isosceles Cu(3) cluster (J(12) not equal J(13) = J(23)), the hyperfine splittings of the EPR spectra of the two split S = 1/2 levels with intermediate spins S(12) = 0 and S(12) = 1 are essentially different. The EPR signal of the |(S(12) = 0)S = 1/2> level is characterized by the four equally spaced hyperfine lines (interval A = a) with the same relative spectral amplitudes 16:16:16:16 and total length 3a. For the |(S(12) = 1)S = 1/2> level, the calculated hyperfine structure represents the spectrum of the 16 hyperfine lines with equal spacing (interval A' = a/3), the spectral intensity distribution 1:1:3:3:5:5:7:7:7:7:5:5:3:3:1:1 and total length 5a. These hyperfine spectra differ from the hyperfine structure (10 lines with interval a/3) of the EPR signals of the excited S = 3/2 level of the Cu(3) cluster. The quartet hyperfine structure, characteristic of a single Cu(2+) nucleus, which was observed experimentally for the doublet ground state of the spin-frustrated Cu(3)(II) clusters, corresponds to the hyperfine structure of the EPR signal of the |(S(12) = 0)S = 1/2> level. This hyperfine structure is evidence of the lowering of the Cu(3) cluster symmetry from trigonal to orthorhombic and the small splitting of the spin-frustrated 2(S = 1/2) ground state.     

Nonadditivity and the stability of Ag3. A multireference configuration interaction study

Variational (?30 000 determinants) and perturbational (?3.5 million determinants) Localized Multireference Configuration Interaction (LMRCI) calculations includingf polarization functions are made to study the role played by the three-body terms in the stabilization energy of three selected geometries of the silver trimer: linear, equilateral and a Jahn-Teller obtuse triangle conformation. A comparative analysis of the relative stability of these geometries is done through a many-body decomposition of the interaction energy. Like in Cu₃, the most symmetrical arrangement (i.e. an equilateral triangle) is found to be less stable than the obtuse triangle because it has the highest three-body repulsion energy. The absolute minimum is the obtuse triangle having a Jahn-Teller stabilization energy of 328 cm^?1. Unlike Cu₃, the linear geometry is found to be less stable than the equilateral by 1282cm^?1. Results show again the importance of three-body terms in the total interaction energy of these trimers.