Recoil spectrometry: Ion accelerator based elemental characterisation of surface layers

Recoil Spectrometry covers a group of techniques that are very similar to the well known Rutherford backscattering Spectrometry technique, but with the important difference that one measures the recoiling target atom rather than the projectile ion. This makes it possible to determine both the identity of the recoil and its depth of origin from its energy and velocity, using a suitable detector system. The incident ion is typically high-energy (30–100MeV)³⁵C1,⁸¹Br or¹²⁷I. Low concentrations of light elements such as C, O and N can be profiled in a heavy matrix such as Fe or GaAs. Here we present an overview of mass and energy dispersive recoil Spectrometry and illustrate its successful use in some typical applications.     

不饱和类锗烯H2C=GeNaBr的密度泛函理论研究

应用密度泛函理论DFT方法,在B3LYP/6-311G(d,p)水平上研究了不饱和类锗烯H2C=GeNaBr的结构及异构化反应.结果表明,不饱和类锗烯H2C=GeNaBr有3种平衡构型,其中非平面的p-配合物型构型能量最低,是其存在的主要构型.并对平衡构型间异构化反应的过渡态进行了计算,求得了转化势垒,预言了最稳定构型的振动频率和红外强度.     

Absence of p,π-conjugation in the Cl2C=CHOMe molecule from data ofab initio calculations

ab initio Calculation of the Cl₂C=CHOMe molecule has been carried out with geometrical optimization in the split valence basis set in the RHF/6-31G^*//RHF/6-31G^* approximation. An analysis of the populations of the p-orbitals of the Cl atoms implies the absence of p,-conjugation between the unshared electron pairs of these atoms and the -bond. The asymmetry parameters of the electric field gradient at the³⁵Cl nuclei, calculated from the 3p-orbital populations of the Cl atoms, practically coincide with the experimental values.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2369–2372, December, 1995.The authors are grateful to G. S. Beloglazov for assistance in accomplishingab initio calculations.     

手性苯并咪唑铜(Ⅱ)络合物催化合成1,1''''-联-2萘酚

In the past several decades, much attention has been paid to optically active, C2-asymmetric 1,1′-binaphthalene-2,2′-diol and its derivatives because of their application in inducing chirality in asymmetric synthesis[1,2]. Enantiomerically pure 1,1′-binaphthalene-2,2′-diol has been prepared by many methods ranging from the classical resolution via crystallization of the diastereoisomeric salts[3] to asymmetric oxidative coupling[4～6].     

{(MesGa)3[GaP(H)Mes](PMes)4}, Ein phosphorsubstituiertes Ga?P-Heterocuban

{(MesGa)₃[GaP(H)Mes](PMes)₄}, a Phosphorus-substituted Ga? P-Heterocubane A mixture of MesGaCl₂/GaCl₃ (ratio 3:1) reacts with 5 equivalents of MesPLi₂ in THF at ?78°C to the title compound {(MesGa)₃[GaP(H)Mes](PMes)₄} ( 1 ) by use of the “dilution principle”. 1 can be obtained in 30% yield. Recrystallization of 1 from DME and toluene, respectively, gives 1 · 0.5 DME and 1 · toluene. 1 was characterized by NMR-, IR-, and MS-techniques. According to the X-ray structure determination of 1 · toluene, 1 has a heterocubane structure, one corner of which is substituted with an P(H)Mes group.     

C(2×2)S/Fe(001)吸附体系的SCF-Xa-MS研究

采用SCF-X_α-MS方法, 对于C(2×2)S/Fe(001)吸附体系, 选择Fe_5S和Fe_9S两种原子簇模型, 研究了该吸附体系的电子结构、吸附成键特征及其相互作用图象。结果表明, S吸附于Fe(001)单晶表面具有较强的定域性质, S原子与底物Fe原子之间的吸附相互作用主要表现为S(3p)-Fe(4s,3d)之间的轨道相互作用。通过对表面吸附键长的优化, 其结果与X.S.Zhang等的ARPEFS的实验结果一致。     

Inhibitory study of some novel Schiff base derivatives on Staphylococcus aureus by microcalorimetry

The effect of a series of novel Schiff base compounds on Staphylococcus aureus was studied by microcalorimetric method at 37 °C The results showed that all of the organic compounds had the capacity to inhibit the growth of S. aureus in different extent. And the extent and duration of the inhibitory effect on the growth of S. aureus, judged from the rate constant (k), varied with the different structure of the Schiff base compounds. According to the power-time curves, the multiplication rate constant and inhibition ratio were calculated. The growth rate constant of S. aureus (in log phase) in the presence of Schiff base compounds decreased with the increasing of the concentrations of these compounds regularly. The experimental results revealed that the hydrophilicity of Schiff bases had a great influence on their antibacterial activity. Of these Schiff bases, the greater their hydrophilicity, the higher their antibacterial activity. The antibacterial structure-activity relationship (SAR) of Schiff base derivatives was also briefly discussed.     

手性3,5-二甲基-2-芳基-2-吗啉醇盐酸盐的合成及其晶体结构

以(S)-2-氨基丙醇为手性源与α-溴-3-氯苯丙酮反应, (R)-2-氨基丙醇为手性源与6-甲氧基-2-(2-溴丙酰基)萘反应, 分别合成了手性纯化合物(2R,3R,5S)-3,5-二甲基-2-(3-氯苯基)-2-吗啉醇盐酸盐(4a)和(2S,3S,5R)-3,5-二甲基-2-(6-甲氧基-2-萘基)-2-吗啉醇盐酸盐(4b), 利用X射线单晶衍射仪测定了两化合物的晶体结构和两化合物的空间结构, 并初步分析两化合物空间结构, 化合物4a晶体属正交晶系, 空间群为P2₁2₁2, 晶胞参数为: a＝0.8718(2) nm, b＝0.7883(2) nm, c＝2.0247(6) nm, Z＝4, V＝1.3915(7) nm³, D_c＝1.328 g/cm³, F(000)＝584, R₁＝0.0399, wR₂＝0.0797, S＝1.042. 化合物4b晶体属正交晶系, 空间群为P2₁2₁2₁, 晶胞参数为: a＝0.71035 (9) nm, b＝0.77703(10) nm, c＝2.9820(4) nm, Z＝4, V＝1.6318(4) nm³, D_c＝1.318 g/cm³, F(000)＝688, R₁＝0.0520, wR₂＝0.1108, S＝0.994.     

Additive telluromolybdates. Structure and catalysis in oxidation

Additive telluromolybdates, MoO₃·2TeO₂ and M^IIO·TeO₂·MoO₃ (M^IITeMoO₆; M^II = Co, Mn, Zn), converted ethyl lactate selectively to pyruvate in a vaporphase fixedbed flow system at 250–300 °C. A synergy in activity was observed for binary TeO₂–MoO₃, and crystalline Te₂MoO₇ was suggested as the active species. The Rietveld analysis of powder XRD patterns of ternary CoTeMoO₆ revealed the layer structure quite different from that of the reference Te₂MoO₇, but tellurium was again located adjacent to molybdenum linked through lattice oxygen.     

Synthesis, structure and magnetic properties of the S=1/2, one-dimensional antiferromagnet, Y5Re2O12

Single crystals of Y₅Re₂O₁₂ have been grown, and the crystal structure has been determined by X-ray diffraction. This compound crystallizes in space group C2/m with cell dimensions of a=12.4081(10) Å b=5.6604(5)Å, c=7.4951(6) Å, β=107.837(3)°, Z=2. The final refinement led to R1=0.0238, WR2=0.0459 for 1053 observed reflections with F>4σ(F₀). Edge-sharing ReO₆ octahedra form infinite linear [ReO₂O_4/2]_n chains along the b direction with alternating short and long Re-Re distances. Three crystallographically independent yttrium atoms surround O2 to form OY₄ tetrahedra, which share edges and corners in the ab plane to form a two-dimensional Y₅O₄ network which separates the [ReO₂O_4/2]_n magnetic chains. This compound is therefore isostructural with the series Ln₅Re₂O₁₂Ln=Gd-Lu, which have been known since 1969. The average Re oxidation state is +4.5 in the chains and a reasonable, if qualitative MO scheme results in one unpaired electron per Re dimer. Consistent with this, magnetic susceptibility data can be fitted to the one-dimensional antiferromagnetic Heisenberg model with S=1/2 and parameters J^intra/k=−89(1)K, g=2.15(4) and χ(TIP)=5(1)×10⁻⁴ emu/mol. There is no sign of long-range magnetic order down to 2 K. These results are contrasted with those for the isostructural Y₅Mo₂O₁₂.