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1.
The 5D 0→ 7F 0-2 emission of Eu 3+ in cordierite is reported. Fluorescence line-narrowed emission by the 5D 0← 7F 0 transition was used to study local structure around the Eu 3+ ion in cordierite glass. It was found that the Eu 3+ ion forms quasi-molecular complexes with the non-bridging oxygen, enabling the FLN data to be accounted for in terms of a single non-random distribution of crystal field strengths. 相似文献
2.
The bimetallic [Pt(NH 3) 4] 2[W(CN) 8][NO 3]·2H 2O is characterised by single-crystal X-ray diffraction [S.G. P2 1/ m(11), a=8.0418(7), b=19.122(2), c=9.0812(6) Å, Z=2]. All platinum centres have the square-plane D4h geometry with average dimensions Pt(1)–N 2.042(2) and Pt(2)–N 2.037(10) Å. The octacyanotungstate anion has the square-antiprismatic D4d configuration with average dimensions W(1)–C 2.164(13), C–N 1.140(12), W(1)–N 3.303(5) Å. The structure exhibits two different mutual orientations of Pt versus W units resulting in Pt(2)–W(1), W(1) * separations of 4.77(2), 4.55(2) * and Pt(1)–W(1) of 6.331(8) Å. A centrosymmetric structure reveals groups of two distinct columns: the first is formed by intercalated NO 3− between parallel [Pt(1)(NH 3) 4] 2+ planes and the second consists of [W(CN) 8] 3− interlayered by, parallel to square faces of W-antiprisms, [Pt(2)(NH 3) 4] 2+. The structure is stabilised through a three-dimensional hydrogen bond network via nitrogen atoms of cyanide ligands, hydrogen atoms of NH 3 ligands, water molecules and oxygen atoms of NO 3− counteranions. The vibrational pattern and the range of ν(CN) frequencies attributable to the electronic environment of W(V) and W(IV) are consistent with the ground state Pt(II)↔W(V) charge transfer. 相似文献
3.
CaSiO3:Eu0.08^3+Bi0.002^3+ with a monoclinic perovskite structure was synthesized by using sol-gel method, and its luminescence characteristics were investigated. From the excitation spectrum, it can be seen that the main peaks located at 238,396,415,437 and 359 nm correspond to the charge-transfer band of Eu^3+-O^2- , the absorption transitions of ^7F0.1→^3L6, ^7F0→^5D3, ^7F1→^5D3 of Eu^3+ ions, and ^3P1→^1S0 of Bi^3+ ions, respectively. When the samples were excited with a light of wavelength 359 or 395 nm, it can be seen from the emission spectrum that the electronic dipole transition located at 609 nm corresponding to ^5D0→^7F2 of Eu^3+ ions was stronger than the magnetic dipole transition located at 587 nm corresponding to ^5D0→^7F1 of Eu^3+ ions, which shows that more Eu^3+ ions were located in nonreversion center lattices. The energy transfer from Bi^3+ ions to Eu^3+ ions in the phosphor was also discussed. The results show that Eu^3+ ions could be well sensitized by ^3+ions, and the energy-transfer pattern between Bi^3+ ions and Eu^3+ ions was resonance energy transfer. 相似文献
4.
Two Schiff bases N, N′-(bis(pyridin-2-yl)benzylidene)propane-1,3-diamine (pbpd) and N, N′-(bis(pyridin-2-yl)formylidene)butane-1,4-diamine (pfbd) have been prepared and used to synthesize copper(II) complexes. Four complexes of the type [Cu(L)(N 3)]X (1–4) [L = pbpd; X = ClO 4 (1); L = pbpd; X = PF 6 (2); L = pfbd; X = ClO 4 (3); L = pfbd; X = PF 6 (4)] have been synthesized and characterized on the basis of microanalytical, spectroscopic, magnetic, electrochemical, luminescence and other physicochemical properties. Two representative complexes of the series, 2 and 3, have been characterized by single crystal X-ray diffraction measurements which reveal that in each complex the copper(II) ion assumes a distorted trigonal bipyramidal environment through coordination of the metal centre by two pyridine N atoms and two imine N atoms of the Schiff base with the fifth position occupied by a N atom of a terminal . They display intraligand 1(π–π *) fluorescence at room temperature and intraligand 3(π–π *) phosphorescence in glassy solutions (MeOH at 77 K). A band (492 nm) observed for the complexes in their solid-state emission spectra is an excimeric emission arising due to an aromatic π–π interaction. Electrochemical electron transfer study reveals Cu II–Cu I reduction in methanolic solutions. 相似文献
5.
The Ca( 1D 2, 3P J) + CH 3 → CaI(A,B) + CH 3 reactions system has been studied by measuring its chemiluminescence under beam-gas conditions. Absolute values of the state-to-state reaction cross-sections were determined at low collision energy
. In addition, the electronic branching ratio and product energy disposal have been determined for each metastable reaction. The major changed observed in the chemiluminescence when comparing the Ca( 1D 2) reaction versus that of Ca( 3P J) is the total yield associated with the former reaction. To the best of our spectral resolution neither the electronic branching ratio e.g. CaI(A)/CaI(B) nor the internal CaI energy disposal change significantly as the metastable Ca( 1D 2)/Ca( 3P J) ratio is varied. In spite of the fact that the Ca( 3P J) reaction is less exoergic, the CaI product appears with a higher fraction of internal energy than that of Ca( 1D 2) reaction. Thus, the fraction of the total energy appearing in CaI internal energy amounts to 57.5% in the Ca( 3P J) reaction while it is 19.3% only for the Ca( 1D 2) reaction. This difference is discussed in the light of a distinct mechanism associated with the attack of the excited Ca atom into the C---I bond. No significant chemiluminescence yield was found for the energetically open CaCH *3 channels. The product chemiluminescence polarization was also measured as a function of the metastable concentration. A significant degree of polarization was found depending upon the specific electronic excitation. The analysis of the polarization emission associated to the parallel CaI(X 2Σ+ ← B 2Σ+) emission led into a strong polarization of the product rotational angular momentum. The comparison of the product rotational alignment for the kinematically identical Ca(1D2, 3PJ, 1P1) + CH3 → CaI* (B2Σ+) + CH3 reaction system showed that the CaI rotational polarization diminishes in the 3PJ → 1D2 → 1P1 sequence, e.g. as the reaction exothermicity increases. In addition the degree of polarization associated with other emission bands as for example CaI(X 2Σ+ ← A 2Π1/2) indicates the presence of a parallel transition which was been interpreted as mixing of Hund's case (a) and (c) appropriate for this heavy CaI diatom produced with a high rotational excitation. 相似文献
6.
Eu-doped ZnO nanoneedles with different doping concentrations were prepared via the facile hydrothermal method.The crystal structure,morphology and photoluminescence property of the ZnO nanoneedles were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),photoluminescence spectroscopy(PL) and Raman spectroscopy.The results show that the europium ions are incorporated into the crystal lattice of ZnO matrix in trivalent ions.The nanoneedles are 2-3 μm in length and 100 nm in the tip diameter.PL and Raman measurements indicate that higher Eu^3+ doping concentration may destroy the crystallization of the nanoneedles and decrease the ratio of IUV/IDLE,which is mainly due to the more defects in the doped ZnO nanoneedles.And the characteristic red emissions of Eu^3+ ions are found by the PL spectroscopy with the Eu^3+doping concentration increasing,which are attributed to the ^5D0→^7F0,^5D0→^7F1 and ^5D0→^7F2 transitions. 相似文献
7.
采用Pechini法合成了白光LED用红色荧光粉La 1.9-xMoO 6:0.10Eu 3+,xLi +(x=0,0.10,0.20,0.25),并对样品分别进行了X射线衍射(XRD)、扫描电子显微镜(SEM)、电子能谱(EDX)以及荧光光谱(PL)等技术手段分析。 PL光谱显示该荧光粉可被近紫外光(395 nm)和蓝光(466 nm)有效激发,产生616和623 nm强的红光发射,归属于Eu 3+的 5D 0→ 7F 2电偶极跃迁。该荧光粉与近紫外LED芯片(370~410 nm)和蓝光LED芯片(450~470 nm)均匹配良好,具有潜在的商业应用价值。 共掺Li +离子作为敏化剂能显著提高荧光粉的发光强度,且最优掺杂量为x=0.20。 相似文献
8.
A novel series of color-tunable single-phased phosphors La 1-x-yPO 4:xEu 3+/yTb 3+(x=0, 0.01, 0.02, 0.03, 0.04, 0.05; y=0, 0.05, 0.10, 0.15, 0.20) was synthesized via microwave-assisted co-precipitation method with diammonium hydrogen phosphate as precipitant. The morphology, crystal structure and photoluminescence properties of the as-prepared samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and fluorescence spectrophotometer. The results reveal that the as-synthesized samples calcined at 1100℃ display spherical morphology with uniform distribution. Upon excitation with 350 nm ultraviolet radiation, the LaPO 4:Eu 3+/Tb 3+ phosphors showed a green light peaking at 543 nm assigned to the characteristic 5D 4- 7F 5 emission of Tb 3+ and a red light peaking at 591 nm corresponding to the characteristic 5D 0- 7F 1 emission of Eu 3+ simultaneously. For the Eu 3+/Tb 3+ co-activated phosphors, Tb 3+ acts as an efficient sensitizer to enhance the emission intensity of Eu 3+ ions. The energy transfer mechanism and the emission color tunability of LaPO 4:Eu 3+/Tb 3+ have been studied. The results indicate that a color-tunable luminescence(from green to white to red) can be achieved by adjusting the Eu 3+/Tb 3+ doping ratio in the LaPO 4 host matrix. 相似文献
9.
The syntheses and structural determination of Nd III and Er III complexes with nitrilotriacetic acid (nta) were reported in this paper. Their crystal and molecular structures and compositions were determined by single-crystal X-ray structure analyses and elemental analyses, respectively. The crystal of K 3[Nd III(nta) 2(H 2O)]·6H 2O complex belongs to monoclinic crystal system and C2/ c space group. The crystal data are as follows: a=1.5490(11) nm, b=1.3028(9) nm, c=2.6237(18) nm, β=96.803(10)°, V=5.257(6) nm 3, Z=8, M=763.89, Dc=1.930 g cm −3, μ=2.535 mm −1 and F(000)=3048. The final R1 and wR1 are 0.0390 and 0.0703 for 4501 ( I>2σ( I)) unique reflections, R2 and wR2 are 0.0758 and 0.0783 for all 10474 reflections, respectively. The Nd IIIN 2O 7 part in the [Nd III(nta) 2(H 2O)] 3− complex anion has a pseudo-monocapped square antiprismatic nine-coordinate structure in which the eight coordinate atoms (two N and six O) are from the two nta ligands and a water molecule coordinate to the central Nd III ion directly. The crystal of the K 3[Er III(nta) 2(H 2O)]·5H 2O complex also belongs to monoclinic crystal system and C2/ c space group. The crystal data are as follows: a=1.5343(5) nm, b=1.2880(4) nm, c=2.6154(8) nm, b=96.033(5)°, V=5.140(3) nm 3, Z=8, M=768.89, Dc=1.987 g cm −3, μ=3.833 mm −1 and F(000)=3032. The final R1 and wR1 are 0.0321 and 0.0671 for 4445 ( I>2σ( I)) unique reflections, R2 and wR2 are 0.0432 and 0.0699 for all 10207 reflections, respectively. The Er IIIN 2O 7 part in the [Er III(nta) 2(H 2O)] 3− complex anion has the same structure as Nd IIIN 2O 7 part in which the eight coordinate atoms (two N and six O) are from the two nta ligands and a water molecule coordinate to the central Nd III ion directly. 相似文献
10.
LnCl 3 (Ln=Nd, Gd) reacts with C 5H 9C 5H 4Na (or K 2C 8H 8) in THF (C 5H 9C 5H 4 = cyclopentylcyclopentadienyl) in the ratio of 1 : to give (C 5H 9C 5H 4)LnCl 2(THF) n (orC 8H 8)LnCl 2(THF) n], which further reacts with K 2C 8H 8 (or C 5H 9C 5H 4Na) in THF to form the litle complexes. If Ln=Nd the complex (C 8H 8)Nd(C 5H 9C 5H 4)(THF) 2 (a) was obtained: when Ln=Gd the 1 : 1 complex [(C 8H 8)Gd(C %H 9)(THF)][(C 8H 8)Gd(C 5H 9H 4)(THF) 2] (b) was obtained in crystalline form. The crystal structure analysis shows that in (C8H8)Ln(C5H9C5H4)(THF)2 (Ln=Nd or Gd), the Cyclopentylcyclopentadieny (η5), cyclooctatetraenyl (η8) and two oxygen atoms from THF are coordinated to Nd3+ (or Gd3+) with coordination number 10. The centroid of the cyclopentadienyl ring (Cp′) in C5H9C5H4 group, cyclooctatetraenyl centroid (COTL) and two oxygens (THF) form a twisted tetrahedron around Nd3+ (or Gd3+). In (C8H8)Gd(C5H9C5H4)(THF), the cyclopentyl-cyclopentadienyl (η5), cyclooctatetraenyl (η8) and one oxygen atom are coordinated to Gd3+ with the coordination number of 9 and Cp′, COT and oxygen atom form a triangular plane around Gd3+, which is almost in the plane (dev. -0.0144 Å). 相似文献
11.
Electronic chemiluminescence from the reaction of selected ground state ( 2S 1/2) or metastable ( 2D 5/2, 2D 3/2) copper atoms with fluorine has been studied using a hollow cathode-flowing afterglow reactor. The observed signal related to the Cu( 2S) and Cu*( 2D) atom densities, indicate that the chemiluminescence cross-section for Cu*( 2D) atoms is about 10 4 times larger than for Cu( 2S) atoms. This strong propensity is explained in terms of a direct reaction, initiated by a harpooning process, during which the Cu + ion core of the reactant (3d 10 for Cu( 2S) and 3d 94s for Cu*( 2D)) is conserved in the products (ionic structure Cu +(3d 10)F − for the CuF ground state and Cu +(3d 94s)F − for the CuF*(a, A, B, C, D) chemiluminescent states). 相似文献
12.
A series of new complexes of formula Ln(acac)_s(Ph_3PO)_3 (where Ln~(3+)=Nd~(3+), Sm~(3+), Eu~(3+), Tb~(3+), Ho~(3+)) have been prepared and characterized. The coordination of two ligands with lanthanide ions are studied by IR spectra, ~1H, ~(13)C, ~(31)P-NMR and metal-ligand charge tranafer tranaition is also discussed via electronic adaorption and luminescence spectroscopy. 相似文献
13.
A novel N6 macrocyclic ligand, L 1 (2,8,14,20-tetramethyl-3,7,15,19,25,26-hexaaza-tricyclo[19.3.1.1 9,13]hexacosa-1(24),9,11,13(26),21(25),22-hexaene), was obtained by reduction of the 2 + 2 condensation product of 2,6-diacetylpyridine and propane-1,3-diamine. Zinc(II) complexes of L 1, of a related N8 macrocycle, L 3 (3,6,9,17,20,23,29,30-octaaza-tricyclo[23.3.1.1[11,15]]triaconta-1(28),1,13,15(30),25(29),26-hexaene), similarly prepared by 2 + 2 condensation of 2,6-diformylpyridine and diethylenetriamine and of a tetra N-2-cyanoethyl derivative of a homologue of L 1 prepared from diformyl pyridine and ethane-1,2-diamine, L 2 (3-[6,14,17-tris-(2-cyano-ethyl)-3,6,14,17,23,24-hexaaza-tricyclo[17.3.1.1 8,12] tetracosa-1(23),8(24),9,11,19,21-hexaen-3-yl]-propionitrile), were prepared. Structures were determined for [ZnL 1](ClO 4) 2 · H 2O, [ZnL 2](NO 3) 2 and [Zn 2L 3(NO 3) 2](NO 3) 2 · H 2O. The [ZnL 1](ClO 4) 2 · H 2O and [ZnL 2](NO 3) 2 complexes present a mononuclear endomacrocyclic structure with the metal in an octahedral distorted environment coordinated by the six donor nitrogen atoms from the macrocyclic backbone while the complex [Zn 2L 3(NO 3) 2](NO 3) 2 · H 2O is dinuclear with both metal atoms into the macrocyclic cavity coordinated by four donor nitrogen atoms from the macrocyclic framework and one oxygen atom from one monodentate nitrate anion, in a distorted square pyramidal arrangement. 相似文献
14.
The reactions of R 2P–P(SiMe 3) 2 (R = Ph, iPr and iPr 2N) with BuLi in THF or DME solution lead to ion-contacted lithium derivatives R 2P–P(SiMe 3)Li · 3THF (R = iPr, iPr 2N) with tetrahedrally surrounded Li atoms and to the solvent-separated ionic [Li · 3DME] +[Ph 2P–PSiMe 3] − with an octahedrally surrounded Li atom as confirmed by X-ray crystal structure analysis. The reaction of BuLi with Ph 2P–P(SiMe 3) 2 is accompanied with a significant side-reaction leading to Ph 2P–PPh 2 and to LiP(SiMe 3) 2. 相似文献
15.
One-dimensional Co(dien) 2(VO 3) 3·(H 2O) was prepared from the hydrothermal reaction of NH 4VO 3, Co 2O 3, diethylenetriamine (dien) and H 2O at 130 °C. The compound crystallizes in the monoclinic system, space group P2 1/ c with a=16.1581(6) Å, b=8.7006(3) Å, c=13.9893(4) Å, β=103.1483(11)°, V=1915.13(11) Å 3, Z=4, and R1=0.0268 for 3060 observed reflections. Single crystal X-ray diffraction revealed that the structure is composed of infinite one-dimensional chains formed by corner-sharing VO 4 tetrahedra with Co(dien) 3+ complex cations and crystallization water molecules occupying the interchain positions, which are held together to a three-dimensional network via extensive hydrogen-bonding interactions. The compound, with a new zig-zag conformation of metavanadate chains, is the first example of vanadium oxides incorporating trivalent transition metal coordination groups. Other characterizations by elemental analysis, IR and thermal analysis are also described. 相似文献
16.
Nickel(II) chromate complex with imidazole (HIm) was isolated from the [Ni 2+–HIm–CrO 42−] system in various experimental conditions, i.e. reagent molar ratios and nickel(II) salts. The catena( μ-CrO 4- O, O′)[Ni(HIm) 3H 2O] (1) crystallizes in monoclinic crystal system—space group P2 1/ n with cell parameters: a=11.784(2), b=8.899(2), c=13.934(3) (Å), β=95.19(3) (°). The unit cell contains two independent helixes, left- and right-handed, stabilized by intrahelical and interhelical hydrogen bonds (HB) and π–π interactions. The cis coordination of the CrO 42− anions and the HB systems appeared to be the main determinants of the helical architecture. To the best of our knowledge the cis-chromate coordination was observed for the first time. The cis coordination causes the distortion of the nickel octahedron, which was analysed by 4 K single crystal electronic spectra with D4h symmetry approximation (gaussian resolution and crystal field parameters). This symmetry was also confirmed with the polarised electronic spectra. The magnetic properties of the complex suggest the occurrence of weak intrachain antiferromagnetic interactions between the magnetic Ni II center. The computational DFT studies of complex 1 assuming three possible isomers mer[(HIm) 3]– cis[(CrO 42−) 2], mer– trans and fac– cis suggested that the main contribution to the stability of 1 might have interhelical and intrahelical hydrogen bonds. 相似文献
17.
The atomic cations of Sr and Mo have been observed to add sequentially up to four molecules of C 60 in helium at 0.35 Torr and room temperature in the flow tube of a modified inductively coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. The available center-of-mass energy in collision-induced dissociation experiments of approximately 1.3 eV failed to remove C 60 from M +(C 60) 4. A structure is proposed for M +(C 60) 4 cations in which the bonding involves η 6 interaction of the metal with the C 60 ligands and η 2-to-η 2 interactions between the C 60 ligands. 相似文献
18.
A quantitative comparison between the excitation and absorption spectra of Eu 3+ in aqueous solution is given which leads to the conclusion that fluorescence quantum yields are independent of the excitation wavelength. Use is made therefore of the series of homologous lines 5D 3, 5D 2, 5D 1, 5D 0 → 7F 1. 相似文献
19.
The molecular and crystal structure of the nido-6-tungstadecaborane [6,6,6,6-(CO) 2(PPh 3) 2- nido-6-WB 9H 13] (1) has been determined showing that the tungsten atom is incorporated into the 6-position of a nido 10-vertex (WB 9) cage. The tungsten atom has a seven-coordinate capped trigonal prismatic environment and is bonded to two hydrogen and three boron atoms of the {B 9H 13} cage, in addition to two CO groups and two PPh 3 ligands. Variable-temperature (−90°C to +50°C) 31P{ 1H} NMR spectroscopy of 1 reveals that the exo-polyhedral ligands about the tungsten atom are fluxional with respect to PPh 3 site exchange with an activation energy (Δ G‡), at the coalescence temperature (−73°C), of <38 kJ mol −1. 相似文献
20.
The compound [Zn(H 2O) 4] 2[H 2As 6V 15O 42(H 2O)]·2H 2O (1) has been synthesized and characterized by elemental analysis, IR, ESR, magnetic measurement, third-order nonlinear property study and single crystal X-ray diffraction analysis. The compound 1 crystallizes in trigonal space group R3, a= b=12.0601(17) Å, c=33.970(7) Å, γ=120°, V=4278.8(12) Å 3, Z=3 and R1( wR2)=0.0512 (0.1171). The crystal structure is constructed from [H 2As 6V 15O 42(H 2O)] 4− anions and [Zn(H 2O) 4] 2+ cations linked through hydrogen bonds into a network. The [H 2As 6V 15O 42(H 2O)] 6− cluster consists of 15 VO 5 square pyramids linked by three As 2O 5 handle-like units. 相似文献
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