Discharge characteristics of the DUHOCAMIS with a high magnetic bottle-shaped field

For the purpose of producing high intensity, multiply charged metal ion beams, the dual hollow cathode ion source for metal ions (DUHOCAMIS) was derived from the hot cathode Penning ion source combined with the hollow cathode sputtering experiments in 2007. To investigate the behavior of this discharge geometry in a stronger magnetic bottle-shaped field, a new test bench for DUHOCAMIS with a high magnetic bottle-shaped field up to 0.6 T has been set up at the Peking University. The experiments with magnetic fields from 0.13 T to 0.52 T have indicated that the discharge behavior is very sensitive to the magnetic flux densities. The slope of discharge curves in a very wide range can be controlled by changing the magnetic field as well as regulated by adjusting the cathode heating power; the production of metallic ions would be much greater than gas ions with the increased magnetic flux density; and the magnetic field has a much higher influence on the DHCD mode than on the PIG mode.     

The Field-Dependent Magnetization of d5–d7 Metal β−Diketonate Complexes and Their Macromolecular Polymers

A vibrating sample magnetometer (VSM) has been used to study the field-dependent magnetization, M(H), of the d⁵?d⁷ metal acetates [M(OAc)₂.nH₂O], metal β?diketonate complexes [M(tba)₂(H₂O)₂] and the macromolecular polymers [M(tba)₂(4,4-bipy)]_n (where, M = Mn(II), Fe(II), and Co(II), OAc = O₂CCH₃, tba = deprotonated 3-benzoyl-1.1.1-trifluoroacetone, and 4,4-bipy = 4,4′-bipyridine). The magnetic field strength (H) was applied in the range of 0?10⁴ O_e at ambient temperature (ca. 23°C). The experimental results showed that the d⁵?d⁷ metal acetate, complexes and polymers exhibit low paramagnetic properties excepting [Fe(tba)₂(4,4-bipy)]_n polymer, which had negative magnetization M(emu/g) showing diamagnetic properties in the range 0?10⁴ O_e. The magnetization was almost equal to zero without an applied magnetic field (H(O_e)) for each d⁵?d⁷ metal acetate, complex, and polymer. The linear M(H) curve had a magnetic saturation for iron and manganese acetate species at the magnetic field strengths of 3.1 × 10³ and 4.7 × 10³ Oe, respectively. The external magnetic field reached 9.0 × 10³ O_e without any saturation magnetization for the cobalt compounds. The coordination effect of 3-benzoyl-1.1.1-trifluoroacetone (H-tba) and 4,4′-bipyridine (4,4′-bipy) ligands on the field-dependent magnetization M(H) and paramagnetic behavior of d⁵?d⁷ metal atoms is discussed. The field-dependent magnetization M(H) curves of metal β?diketonate complexes and the polymers including d⁵?d⁷ metal acetates showed a weak field octahedral geometry.     

BGP reflection functors in root categories

We define the BGP-reflection functors in the derived categories and the root categories. By Ringel's Hall algebra approach, the BGP-reflection functor is applicable to obtain the classical Weyl group action on the Lie algebra.     

二（2,4,4—三甲基戊基）膦酸稀土配合物的振动光谱

测定了二（２，４，４－三甲基戊基）膦酸（ＢＴＭＰＰＡ）及其稀土配合物Ｌｎ（ＢＴＭＰＰ）３在４０００～５０ｃｍ＾－１光谱区内的ＦＴ－ＩＲ光谱和部分配合物的激光拉曼光谱，对其谱带进行了经验归属。发现稀土氧键具有较高的离子键特性。由Ｌｎ－Ｏ伸缩振动频率值算出其近似力常数约８ｍ ｄｙｎ／ｎｍ。     

Interplay of Antiferromagnetic Coupling and Spin Crossover in Dinuclear Iron(II) Complexes

This article reports on the study of the interplay between magnetic coupling and spin transition in 2,2′-bipyrimidine (bpym)-bridged iron(II) dinuclear compounds. Coexistence of both phenomena has been observed in [Fe(bpym)(NCS)₂]₂bpym, [Fe(bpym)(NCSe)₂]₂bpym and [Fe(bt)(NCS)₂]₂bpym (bpym = 2,2′-bipyrimidine, bt = 2,2′-bithiazoline) by the action of external physical factors namely pressure or electromagnetic radiation. Competition between magnetic exchange and spin crossover has been studied in [Fe(bpym)(NCS)₂]₂bpym at 6.3 kbar. LIESST experiments carried out in [Fe(bpym)(NCSe)₂]₂bpym and [Fe(bt)(NCS)₂]₂bpym at 4.2 K have shown that is possible to achieve dinuclear molecules with different spin states in this class of compounds. This revised version was published online in August 2006 with corrections to the Cover Date.     

Homotopy Theories of Algebras over Operads

Homotopy theories of algebras over operads, including operads over “little n-cubes,” are defined. Spectral sequences are constructed and the corresponding homotopy groups are calculated.__________Translated from Matematicheskie Zametki, vol. 78, no. 2, 2005, pp. 278–285.Original Russian Text Copyright © 2005 by V. A. Smirnov.     

Metal insulator transition characteristics of macro-size single domain VO2 crystals

The metal insulator transition (MIT) characteristics of macro-size single-domain VO₂ crystal were investigated. At the MIT, the VO₂ crystal exhibited a rectangular shape hysteresis curve, a large change in resistance between the insulating and the metallic phases, in the order of ～10⁵, and a small transition width (i.e. temperature difference before and after MIT) as small as 10^?3°C. These MIT characteristics of the VO₂ crystals are discussed in terms of phase boundary motion and the possibility of controlling the speed of the phase boundary, with change in size of crystal, is suggested.     

Energy transfer from a polymer host to a europium complex in light-emitting diodes

Energy transfer leading to electroluminescence of a lanthanide complex, Eu(Fod)₃MK (Fod=heptafluoro-dimethyl-octanedionate, MK=4, 4′-bis(N,N-dimethylaminobenzophenone) doped into PVK host is investigated. The optical properties of pure Eu(Fod)₃MK and its doping in PVK show that the PVK host can efficiently transfer energy to europium ions through a co-ligand of MK due to good spectrally overlap. Light-emitting diodes (LED) consisting of PVK doped with 1-5 wt% of Eu(Fod)₃MK also demonstrates this energy transfer. Organolanthanide complexes doped into a wide-gap conducting polymers would lead to efficient and pure red organic LEDs to solve the full colour conjugated polymer displays.     

Photophysical properties of a series of high luminescent europium complexes with fluorinated ligands

A series of high luminescent europium complexes have been synthesized, such as Eu(TFNB)₃phen (1), Eu(PFNP)₃phen (2), Eu(HFNH)₃phen (3) and Eu(PFND)₃phen (4), which have β-diketone ligands containing fluorinated alkyl chains with different lengths and conjugated naphthyl groups, i.e., 4,4,4-trifluoro-1-(2-naphthyl)butane-1,3-dione (TFNB); 4,4,5,5,5-pentafluoro-1-(2-naphthyl)pentane-1,3-dione (PFNP); 4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)hexane-1,3-dione (HFNH) and 4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-pentadecafluoro-1-(2-naphthyl)decane-1,3-dione (PFND). And 10-phenanthroline (phen) is coordinated as the neutral second ligand in 1-4. The crystal structures of 1 and 2 have been studied, which are typical and similar to that of 3. The results of TGA-DTA suggest that these Eu complexes have good thermal stabilities. By means of absorption and (time resolved) emission spectroscopy including determination of luminescence quantum yields, energy transfer dynamics and so on, the following results have been obtained: first, these Eu complexes show characteristic pure red color photoluminescence emission with high quantum efficiencies from the central Eu³⁺ ions through the excitation of the ligands; secondly, photophysical properties of 1, 2, 3 and 4, especially the lifetimes of excited states ⁵D₀ of Eu³⁺ ions and quantum efficiencies are influenced by the different lengths of fluorinated alkyl chains, though the singlets (S₁) and triplets (T₁) of the fluorinated ligands are almost the same.     

Characterisation of Interfaces Between Liquid Tin and Alumina in the Presence of Titanium Alloy Additions

Neutron reflection spectroscopy has been used to characterise the composition of interfaces between liquid Sn-Ti alloys and Al₂O₃. The reflectivity profiles for both 1% and 3% Ti alloys are consistent with the presence of a layer approximately 2 nm thick at the liquid/solid interface, showing extensive segregation of Ti. The composition of this layer is not pure Ti but shows a greater Ti content than any known Ti oxide composition. In all interfaces exposed to liquid metals at elevated temperature (including pure Sn) there is a layer of thickness 20–100 nm on the alumina surface with slightly lower neutron scattering length density than pure alumina. This is interpreted as evidence for surface roughening of the Al₂O₃ surface during exposure to the liquid metal.