低温固相反应合成苯乙酸稀土配合物及铕(Ⅲ)、铽(Ⅲ)的发光性能

采用低温固相反应合成了4种苯乙酸稀土配合物:RE(L)3.nH2O(n=0.5～1.5;RE=La,Nd,Eu,Tb;L=C6H5CH2COO-),经元素分析、稀土络合滴定、摩尔电导及热重分析确定了配合物的组成,测定了配体及配合物的IR谱、1HNMR及配体的磷光光谱和铕、铽配合物荧光激发和发射光谱。根据磷光发射光谱数据计算了配体的三重态平均能级值。铕(Ⅲ)、铽(Ⅲ)配合物的荧光光谱和配体的磷光光谱表明,配体仅对铽(Ⅲ)的荧光具有一定的敏化作用。对镧配合物进行了扫描电镜形貌分析,发现苯乙酸镧为球状空穴结构,粒径在十几微米到几十微米。     

铕与苯甲酸及其衍生物配合物的光谱分析

合成了铕与苯甲酸及其衍生物(苯甲酸、邻苯二甲酸、间苯二甲酸、水杨酸、邻氨基苯甲酸、磺基水杨酸)的二元配合物.经元素分析确定其组成式.研究了它们的红外吸收光谱、紫外吸收光谱及荧光光谱.紫外光谱的研究表明,配合物的紫外吸收主要表现为配体的吸收.红外光谱的研究表明,配合物的红外光谱不同于自由配体的红外光谱,证明了稀土与有机物形成了配合物.荧光光谱的研究表明,其中铕与苯甲酸、邻苯二甲酸及间苯二甲酸形成的配合物表现出铕的特征荧光.其中以苯甲酸铕的发射峰最强,最强发射峰位于λ=618nm处,显示铕的红光特征;而铕与磺基水杨酸、邻氨基苯甲酸、水杨酸的配合物却主要表现出配体的宽带发射,其中邻氨基苯甲酸铕分别在λ=399,452,547nm处有三个弱的发射峰,磺基水杨酸铕也只在λ=407nm处有一宽发射峰,未显示出铕的红光特征.     

铕(Ⅲ)配合物的合成及发光性能研究

分别以1,10-邻菲咯啉、三苯基氧磷、2,2’-联吡啶为第二配体,以苯甲酰丙酮为第一配体,合成了3种铕(Ⅲ)配合物。通过红外光谱、紫外-可见光吸收光谱和荧光光谱对其性能进行了表征。初步从理论上探讨了不同的第二配体对铕(Ⅲ)配合物光致发光性能的影响,并建立了分子内能量传递模型。结果表明：配体和配合物对紫外光都有强烈吸收,所有配合物在紫外光激发下均能发射Eu3+的特征荧光;第二配体与Eu3+间的能级差以及第一配体与第二配体间的能级差都会影响铕(Ⅲ)配合物的荧光量子效率。     

新型Eu~(3+)、Tb~(3+)掺杂配合物的合成与荧光性能研究

合成了稀土(Eu3+和Tb3+)与二苯甲酰甲烷(DBM)、2,2′-联吡啶(Dipy)的一系列稀土配合物EuxTb1-x(DBM)3Dipy。元素分析和红外分析确定了配合物的组成,荧光光谱研究了荧光性质。铽掺入配合物后,铽能极大地增强铕的特征荧光,铽对铕配合物的发光有协同作用。在该系列配合物中,不仅有机配体可以将吸收的能量传递给发光的铕离子使其发光,而且铽离子也可将其吸收的能量通过分子内能量传递给铕离子。     

稀土掺杂铕(Ⅲ)二苯甲酰甲烷邻菲咯啉三元配合物的合成和荧光性质

合成了 3个系列稀土掺杂铕二苯甲酰甲烷 (Hdbm)邻菲咯啉 (phen)三元配合物 Eux RE1 -x(dbm) 3 phen(RE=La,Y,Gd;x=0 .0 0、0 .1 0、0 .30、0 .5 0、0 .70、0 .80、0 .90、1 .0 0 ) ,通过元素分析、摩尔电导率、红外光谱、X射线粉末衍射对配合物进行了表征。对各配合物系列进行荧光光谱研究 ,发现 L a3 、Y3 和 Gd3 对Eu3 离子均有荧光增敏作用 ,其荧光增敏顺序为 L a3 >Y3 >Gd3 。     

铕(Ⅲ)多核配合物的形成及其荧光增强效应

利用荧光增强效应合成了铕（Ⅲ）异多核固体配合物, 通过元素分析、等离子体发射光谱、红外光谱、荧光光谱等测试手段研究了配合物的组成、结构和发光性质． 结果表明增强离子Ｇｄ３＋ 、Ｌａ３＋ 和Ｙ３＋ 离子的加入能显著的提高配合物中Ｅｕ３＋ 中心的发光强度, 这种荧光效应能减少较为昂贵的铕在配合物中的用量, 从而降低产品的成本．     

铕(Ⅲ)-呋喃甲酸配合物的光谱表征

以硝酸铕 ,呋喃甲酸和邻菲咯啉 (phen)合成了配合物 [Eu(FA) 3·2H2 O]·NO3(4 ,4’ Hbpy) ,[Eu(FA) 3·phen]H2 O和Eu(FA) 2 ·NO3·phen。用元素分析、红外吸收光谱、紫外吸收光谱和溶液荧光光谱对配合物进行了组成确定和表征。溶液荧光光谱表明 ,配合物 [Eu(FA) 3·2H2 O]·NO3(4 ,4’ Hbpy)的发光强度比混配配合物Eu(FA) 2 ·NO3·phen和 [Eu(FA) 3·phen]H2 O的发光强度小很多 ,而且发光寿命较短 ,三元配合物 [Eu(FA) 3·phen]H2 O的发光强度比四元配合物Eu(FA) 2 ·NO3·phen的发光强度略大     

二苯甲酰基甲烷2,2′-联吡啶混合稀土配合物中钆、钇对铕发光的影响

在乙醇溶液中合成了以二苯甲酰基甲烷 (DBM )和 2 ,2′联吡啶 (Dipy)为配体 ,三价铕、等摩尔三价铕 钆及等摩尔三价铕 钇混合稀土为中心体的配合物。测定了配合物的组成 ,研究了其红外光谱和荧光光谱。结果表明 :配合物的最佳激发波长为 4 2 5nm ;在 4 2 5nm波长光激发下 ,配合物发出较强的荧光 ;不发光的Gd3 + 和Y3 + 离子对Eu3 + 离子的发光有一定增强作用 ,其中钇使铕的荧光发射增强大于钆 ;这两个不发光稀土离子对铕的发射峰位影响不大     

铕与苯甲酸、邻菲啰啉系列配合物的合成和光谱分析

合成了铕与苯甲酸(BA)二元配合物及铕与BA、邻菲啰啉(Phen)三元配合物,研究了配合物的红外、紫外吸收光谱及荧光光谱.紫外光谱的研究表明,配合物的紫外吸收主要表现为配体的吸收,配体吸收能量传递给中心离子Eu3+.配合物红外光谱不同于配体的红外光谱,羧基的对称伸缩振动vm (coo-)移至1418cm-1,反对称伸缩振动vaa(COO-)移至1562cm-1,表明稀土与配体之间形成了配位键;测定了配合物及其防伪油墨的荧光性能,铕与苯甲酸、邻菲啰啉形成的三元配合物表现出中心离子Eu3+的特征荧光,616nm荧光发射最强谱蜂对应Eu3+的5D0→7F2跃迁.制备的稀土荧光防伪油墨在可见光下印迹无色,在紫外灯下呈现明显红色荧光.     

二苯甲酰基甲烷2,2''-联吡啶混合稀土配合物中钆、钇对铕发光的影响

在乙醇溶液中合成了以二苯甲酰基甲烷(DBM)和2,2'联吡啶(Dipy)为配体,三价铕、等摩尔三价铕-钆及等摩尔三价铕-钇混合稀土为中心体的配合物.测定了配合物的组成,研究了其红外光谱和荧光光谱.结果表明:配合物的最佳激发波长为425nm;在425nm波长光激发下,配合物发出较强的荧光;不发光的Gd3+和Y3+离子对Eu3+离子的发光有一定增强作用,其中钇使铕的荧光发射增强大于钆;这两个不发光稀土离子对铕的发射峰位影响不大.     

电子自金属电极向Fe^3＋（H2O）6离子转移的几率

用微扰法计算了电子自金属电极向Ｆｅ３＋（Ｈ２Ｏ）６离子转移的几率，其中，利用了Ｆｅ２＋离子３ｄ态被六个配位水分子微扰后的波函数。     

First-principles calculations on implanted TiO<Subscript>2</Subscript> by 3d transition metal ions

3d transition metal (V, Cr and Fe) ions are implanted into TiO₂ by the method of metal ion implantation. The electronic band structures of TiO₂ films doped 3d transition metal ions have been analyzed by ab initio band calculations based on a self-consistent full-potential linearized augmented plane-wave method within the first-principle formalism. Influence of implantation on TiO₂ films is examined by the method of UV-visible spectrometry. The results of experiment and calculation show that the optical band gap of TiO₂ films is narrowed by ion implantation. The calculation shows that the 3d state of V, Cr and Fe ions plays a significant role in red shift of UV-Vis absorbance spectrum.     

Cems study of Sn ion induced reaction in a tin-iron oxide bilayer

This paper studied the chemical reaction between Sn and Fe-oxide by Sn ion mixing. Both Sn and Fe CEMS were used to detect the change of chemical states at the interface of a Sn−Fe oxides bilayer before and after irradiation. It was found that ion mixing induced the reduction of Fe₂O₃ to an FeO state and an Fe−Sn−O ternary compound might have formed.     

Origin of ferromagnetism in iron implanted rutile single crystals

⁵⁷Fe doped titanium oxide monocrystals, prepared by ion implantation at different temperatures and subsequent thermal treatment, were characterized by conversion electron Mössbauer spectrometry, synchrotron radiation x-ray diffraction and superconducting quantum interference device magnetometry. After implantation at room temperature Fe is present in divalent state. Upon annealing in high vacuum Fe^2?+? is reduced to metallic Fe for the most part. After implantation at 623 K most iron is in metallic state. During annealing on air Fe is gradually oxidized from Fe^2?+? to Fe^3?+?. Depending on preparation conditions and thermal treatment the role of different nanosized secondary phases is discussed in terms of their influence on the magnetic properties of Fe:TiO₂. α-Fe nanoparticles are found to be responsible for ferromagnetism observed in TiO₂.     

Large transient magnetic fields at high ion velocities in polarized iron

Nuclear spin precessions due to the transient magnetic field in polarized Fe have been measured as a function of the initial velocity of²⁸Si ions in the first-excited nuclear state. The transient field was found to increase linearly with the ion velocityv in the regionv/c=0.006–0.049. This is in contrast to the Lindhard and Winther model, which requires an inverse proportionality with ion velocity. Reanalysis of an earlier measurement on³⁰Si(2 ₁ ⁺ ) with the linear velocity dependence yields a reduced value for theg-factor ofg=0.37±0.12. Other available velocity-dependent data for²²Ne,⁵⁶Fe and¹⁹⁶Pt are consistent with a linear velocity dependence and suggest in addition a linear dependence on the nuclear charge Z of the moving ion. The increase of the transient field with recoil velocity can be explained semi-quantitatively by the capture of polarized Fe electrons into 1s and 2s vacancies in the moving ion. The velocity-dependent data and other discrepancies from the Lindhard and Winther model for¹⁶N,¹⁸O and very recently, for¹²C are also discussed in terms of the proposed microscopic model.     

Iron Species Present in Fe/ZSM-5 Catalysts – Influence of the Preparation Method

The Fe species present in Fe/ZSM-5 catalysts prepared by ionic exchange in aqueous solution or in the solid state are investigated. The samples were characterized by XRD, EPR, Mössbauer Spectroscopy (MOS-S) and chemical analysis. XRD showed that the peak intensity decreased with the increase in Fe content in the samples. EPR and MOS-S showed that the Fe atoms in all the activated samples appear as Fe⁺³, independently of the method used in the catalyst preparation. The MOS-S data also showed that Fe/ZSM-5, prepared by ion exchange in the solid state presented lower hematite content and more Fe species in charge-compensation sites, the responsible for the catalytic activity, as confirmed by the behavior in the propane oxidation.     

Line emission and alignment effects in state selective electron transfer in He2+-Li(2s, 2pΣ, 2pΠ) collisions

Classical Trajectory Monte-Carlo (CTMC) method has been used to investigate state selective electron capture by He²⁺ ions colliding with Li(2s) and Li(2p) in as well as alignments in the energy range 1-15 keV/amu. He⁺(4l) electron capture, line emission [He II(n = 4 3)] cross-sections and alignment parameters have been calculated and analyzed in the light of the available results. The undulatory structure of the capture and emission cross-sections have been explained qualitatively in terms of a quasi-molecular ion formation. Projectile impact energy and spatial overlap play crucial role in determining the alignment effects. Received 3 July 1998 and Received in final form 3 June 1999     

Isotropic paramagnetic hyperfine interaction: observed at matrix isolated57Fe ions in argon

A clean paramagnetic⁵⁷Fe Mössbauer spectrum due to an isotropic hyperfine interaction was observed at “almost free” Fe atoms in a frozen argon matrix. It was obtained by ion implantation λ⁵⁷Co in an argon matrix at 4.2 K and it is due to⁵⁹Fe⁺(3d⁷) ions in a magnetically isotropic Γ₆ or Γ₇ Kramers state. The hyperfine coupling constant of the free⁵⁷Fe⁺(3d⁷) ion in the nuclear groundstate is deduced to be A=5.0(3), 7.9(5) or 11.1(6) MHz, depending whether the Fe⁺(3d⁷) is in a J=9/2, 7/2 or 5/2 state respectively.     

Site-selective detection of vibrational modes of an iron atom in a trinuclear complex

Nuclear inelastic scattering (NIS) experiments on the trinuclear complex [⁵⁷Fe{L-N₄(CH₂Fc)₂} (CH₃CN)₂](ClO₄)₂ have been performed. The octahedral iron ion in the complex was labelled with ⁵⁷Fe and thereby exclusively the vibrational modes of this iron ion have been detected with NIS. The analysis of nuclear forward scattering (NFS) data yields a ferrous low-spin state for the ⁵⁷Fe labelled iron ion. The simulation of the partial density of states (pDOS) for the octahedral low-spin iron(II) ion of the complex by density functional theory (DFT) calculations is in excellent agreement with the experimental pDOS of the complex determined from the NIS data obtained at 80 K. Thereby it was possible to assign almost each of the experimentally observed NIS bands to the corresponding molecular vibrational modes.     

Investigation of ion-atom collision dynamics through imaging techniques

The principle and technique details of recoil ion momentum imaging are discussed and summarized. The recoil ion momentum spectroscopy built at the Institute of Modern Physics (Lanzhou) is presented. The first results obtained at the setup are analyzed. For 30 keV He²⁺ on He collision, it is found that the capture of single electron occurs dominantly into the first excited states, and the related scattering angle results show that the ground state capture occurs at large impact parameters, while the capture into excited states occurs at small impact parameters. The results manifest the collision dynamics for the sub-femto-second process can be studied through the techniques uniquely. Finally, the future possibilities of applications of the recoil ion momentum spectroscopy in other fields are outlined. Supported by the National Natural Science Foundation of China (Grant No. 10434100)