Dy3+在Ba3La(BO3)3 中的光致发光

研究了Ba3La(BO3)3 基质中Dy3 的光致发光特性; 探讨了RE3 的电荷半径比(z/r)和Ce3 , Dy3 含量对Dy3 发光强度及发光颜色的影响; 分析了Ba3La(BO3)3 中Ce3 对Dy3 发光的敏化作用; 确定了Dy3 的 4F9/2→6H15/2及4F9/2→6H13/2跃迁发射的浓度猝灭机制均为电偶极-电四极相互作用.     

Interaction in Systems Ln2O3-CsPO3 and Ln2O3- UO3-CPO3

Abstract

The systems Ln₂O₃-CsPO₃ and Ln₂O₃-UO₃-CsPO₃ were investigated and three sets of compounds A, B, C were isolated.     

3-nitro- and 3-bromo-3-nitroacrylates in reactions with phenyl azide

1,3-Dipolar cycloaddition of alkyl 3-nitro-and 3-bromo-3-nitroacrylates to phenyl azide gives regioisomeric alkyl 5(4)-nitro-1-phenyl-4,5-dihydro-1H-1,2,3-triazole-4(5)-carboxylates, the corresponding triazoles both with and without nitro group, and alkyl 3-nitro-1-phenylaziridine-2-carboxylates. Nitrotriazolecarboxylates were found to lose the ester moiety during chromatographic separation of the products on aluminum oxide. The structure of the products was determined on the basis of IR, ¹H NMR, and X-ray diffraction data.     

Electrochemical Oxidation of Tantalum in LiNO3-NaNO3-KNO3 Melt

Growth kinetics of anodic oxide films on tantalum in a molten eutectic mixture of lithium, sodium, and potassium nitrates was studied and the influence exerted by introduction of hydroxide and chromate ions into the nitrate mixture was considered. The basic kinetic parameters of anodic oxidation of tantalum under galvanostatic conditions were determined.     

Studies in 3-oxy-assisted 3-aza cope rearrangements

On thermolysis appropriately substituted N-silyloxy-N-allyl enamines undergo smooth 3,3-sigmatropic rearrangments to the corresponding N-silyloxy imino ethers.     

Synthesis and Upconversion Luminescence in LaF3:Yb3+, Ho3+, GdF3: Yb3+, Tm3+ and YF3:Yb3+, Er3+ obtained from Sulfide Precursors

Rare earth fluorides are mainly obtained from aqueous solutions of oxygen‐containing precursors. Probably, this method is simple and efficient, however, oxygen may partially be retained in the fluoride structure. We offer an alternative method: obtaining fluorides and solid solutions based on them from an oxygen‐free precursor. As starting materials, we choose sulfides of rare‐earth elements and solid solutions based on them. The fluorination is carried out by exposure to hydrofluoric acid of various concentrations. The transmission electron microscopy images revealed the different morphologies of the products, which depend on the concentration of the fluorinating component (HF) and the host element. The solid solution particle size varied from 30–35 nm in the case of GdF₃:Yb³⁺, Tm³⁺ (4 % HF) to larger structures with dimensions exceeding 200 nm, such as that for LaF₃:Yb³⁺, Ho³⁺ (40 % HF). The thermal characteristics, such as the temperatures of the transitions and melting and enthalpies, were determined for the solid solutions and simple fluorides. Applicability of the materials obtained as biological luminescent markers was tested on the example of upconversion luminescence, and good upconversion properties were detected.     

KMgF3:Ce3+,Tb3+纳米粒子中Ce3+→Tb3+的发光及能量传递

利用微乳液方法,合成了铈、铽共掺杂的氟镁钾纳米粒子,研究了体系中Ce3+→Tb3+的发光特性以及它们之间的相互作用,结果表明KMgF3:Ce3+Tb3+纳米粒子中存在Ce3+→Tb3+的能量传递过程,即Ce3+可以将吸收的能量直接传递给Tb3+离子,使得Tb3+的绿色发光强度大为增加.     

A comparison of local structures in crystalline P(EO)3LiCF3SO3 and glyme-LiCF3SO3 systems

The newly discovered crystal structures of CH₃(OCH₂CH₂)OCH₃(LiCF₃SO₃)₂, monoglyme:(LiTf)₂, and CH₃(OCH₂CH₂)₃OCH₃(LiCF₃SO₃)₂, triglyme:(LiTf)₂, are briefly described. The coordination of lithium cations and the CF₃SO₃⁻ anions in these structures is compared with the cation and anion coordination in the crystalline phase of high molecular weight P(EO)₃LiCF₃SO₃. Comparison is also made with the previously reported crystalline phase of CH₃(OCH₂CH₂)₂OCH₃LiCF₃SO₃, diglyme:LiTf. A tendency to form trans-gauche-trans conformations for the bond order -O-C-C-O- is noted in adjacent ethylene oxide sequences interacting with a five-coordinate lithium ion.     

Hydrogen bonding in the LaNi3BH3 hydride

The electronic structure of the intermetallic LaNi3B as well as the novel hydride LaNi3BH3 have been theoretically investigated by means of quantum chemistry methods. We employed a mixed approach to investigate the electronic structure of these compounds: state-of-the-art energy band calculations and molecular cluster computations. We computed the energy bands and the total and partial density of states using both the linear-augmented plane waves and projector-augmented wave methods. In addition the electronic structure of three representative clusters of the local environment of Ni atoms was investigated by quantum chemistry ab initio molecular calculations. In this report, we discuss the chemical bonding and we investigated the H site occupancy energies and correlate this estimate with the occupancy fraction and metal-hydrogen distances experimentally observed.     

Phase Equilibria in the System CaSiO3-BaGeO3

The phase relationships in the system CaSiO₃-BaGeO₃ were studied and its phase diagram was constructed.     

Nd3+:LaCl3中的上转换发光研究

当用582.6 nm的黄色激光激发Nd3+:LaCl3的2G7/2+4G5/2能级时,观察到了4D3/2和2G9/2能级的兰光和紫外发射.研究表明,2D3/2上转换的机理是能量传递和激发态吸收,而2G9/2则是由于4G5/2+4Gs/2→2G9/2+4F7/2交叉驰豫过程.通过对12K下4D3/2→4I11/2荧光衰减曲线的分析,得出能量传递几率为wt1＝1468 s-1.测量和讨论了Nd3+:LaCl3和NdCl3主要发光能级室温和12K下的寿命.     

Low-temperature Ce3+ luminescence in CsCdBr3 crystals

Ce³⁺-doped CsCdBr₃ shows several Ce³⁺ emissions due to a diversity of luminescent centers. The nature of these centers is discussed.     

Thermal decomposition of 3-chloro-3-trichloromethyldiazirine in solution

The thermal decomposition of 3-chloro-3-trichloromethyldizairine in carbon tetrachloride and iso-octane has been investigated over the temperature range 75–115°C. The products, tetrachloroethylene and nitrogen, are formed quantitatively by a first-order reaction which is probably unimolecular: The results yielded the following Arrhenius equations: .     

Nonadiabatic coupling in the 3 3Pi and 4 3Pi states of NaK

The excited 3 (3)Pi and 4 (3)Pi electronic states of the NaK molecule exhibit an avoided crossing, leading to the anomalous behavior of many features of the rovibrational energy levels belonging to each state. A joint experimental and theoretical investigation of these states has been carried out. Experimental measurements of the vibrational, rotational, and hyperfine structure of numerous levels of the 3 (3)Pi state were recently obtained using the Doppler-free, perturbation-facilitated optical-optical double resonance technique. Additional measurements for the 4 (3)Pi state as well as bound-free emission spectra from selected 3 (3)Pi, 4 (3)Pi, and mixed 3 (3)Pi to approximately 4 (3)Pi rovibrational levels are reported here. A model is also presented for calculating the mixed rovibrational level energies of the coupled 3 (3)Pi-4 (3)Pi system, starting from a 2x2 diabatic electronic Hamiltonian. The 3 (3)Pi and 4 (3)Pi potential curves and the coupling between them are simultaneously adjusted to fit the observed rovibrational levels of both states. The energy levels of the potential curves determined by the fit are in excellent agreement with experiment. The nonadiabatic coupling is sufficiently strong to cause an overall shift of 2-3 cm(-1) for many rovibrational levels as well as somewhat larger shifts for certain pairs of 3 (3)Pi to approximately 4 (3)Pi levels that would otherwise be very close together.