Quantum states in fabricating poly-Si films

The quantum states are presented in these processions of fabricating poly-Si films. Amorphous silicon films prepared by PECVD has been crystallized by conventional furnace annealing (FA) and rapid thermal annealing (RTA), respectively. It is found that the thin films grain size present quantum states with the increasing of the gas flow ratios of SiH₄, H₂ mixture, substrate temperatures, frequency power, annealing temperature and time.     

Electrochemical and structural investigations of oxide films anodically formed on ruthenium-plated titanium electrodes in sulfuric acid

The electrochemical characteristics of ruthenium oxides, formed on Ru-plated Ti electrodes in 0.5 M H₂SO₄ by potential cycling with different CV upper potential limits (E _SU), were systematically compared. The repeated potential cycling between 0.2 and 0.75 V activated the formation/reduction of surface Ru oxides with hysteretic behavior. This application of repeated CVs also modified the ability of Ru deposits for hydrogen adsorption/desorption. An irreducible Ru oxide accumulated on the electrode at potentials more positive than ca. 0.95 V, whose capacitive characteristics are applicable for electrochemical supercapacitors. This irreducible oxide was composed of an aggregate consisting of Ru in various oxidation states, bridged oxygen, OH and water in a 3D-like structure with a relatively ordered and compact nature, from the X-ray photoelectron spectroscopic and voltammetric results. The surface reconstruction of the Ru deposits induced by the repeated potential cycling with E _SU≥0.75 V was clearly observed from the SEM photographs. From the X-ray diffraction patterns, all the anodically formed Ru oxides showed an amorphous nature.     

3-(水杨酰肼)-丁基-2-酮肟和两个镍的酮肟配合物的合成和晶体结构

合成了3-(水杨酰肼)-丁基-2-酮肟H₂L(1，C₁₁H₁₃N₃O₃)和2个镍的3-(水杨酰肼)-丁基-2-酮肟化合物[Ni(HL)(CH₃COO^-)(C₅H₅N)₂](2)和[Ni(HL)₂]·2C₃H₇NO（3）。化合物1晶体属单斜晶系，空间群为P2₁/n，晶体学参数为：a=0.451 87(2) nm，b=2.086 8(1) nm，c=1.224 48(9) nm，β=94.974(3)°，V=1.150 3(1) nm³，Z=4，D_c=1.358 g·cm^-3，μ=0.101 mm^-1，F(000)=496，R=0.0435，wR=0.142 5。化合物2晶体属单斜晶系，空间群为P2₁/n，晶体学参数为：a=1.362 39(8) nm，b=1.345 37(6) nm，c=1.438 54(7) nm，β=113.138(3)°，V=2.424 6(2) nm³，Z=4，D_c=1.398 g·cm^-3，μ=0.843mm^-1，F(000)=1 064，R=0.042 4，wR=0.116 6。化合物3晶体属单斜晶系，空间群为P2₁/c，晶体学参数为：a=1.104 22(7) nm，b=2.860 1(1) nm，c=1.114 13(7)nm，β=114.589(5)°，V=3.199 5(3) nm³，Z=4，D_c=1.398 g·cm^-3，μ=0.667 mm^-1，F(000)=1 416，R=0.057 6，wR=0.1535。在化合物1晶体中，酮肟分子之间通过分子间氢键形成二维网状结构。在化合物2中，每个镍(Ⅱ)离子由1个3-(水杨酰肼)-丁基-2-酮肟的2个氮原子和1个氧原子，2个吡啶分子中的2个氮原子和1个乙酸根中的1个氧原子形成畸变的NiN₄O₂八面体配位构型，存在分子内氢键O-H(肟)…O(乙酸根)和O-H(酚)…N(酰肼)。在化合物3晶体中，每个镍(Ⅱ)离子由2个3-(水杨酰肼)-丁基-2-酮肟的4个氮原子和2个氧原子配位，形成畸变的NiN₄O₂八面体配位构型。晶体中存在O-H…O和O-H…N两种分子内氢键和O-H…O分子间氢键。     

Trapped interfacial redox introduces reversibility in the oxygen reduction reaction in a non-aqueous Ca2+ electrolyte

Electrochemical investigations of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have been conducted in a Ca²⁺-containing dimethyl sulfoxide electrolyte. While the ORR appears irreversible, the introduction of a tetrabutylammonium perchlorate (TBAClO₄) co-salt in excess concentrations results in the gradual appearance of a quasi-reversible OER process. Combining the results of systematic cyclic voltammetry investigations, the degree of reversibility depends on the ion pair competition between Ca²⁺ and TBA⁺ cations to interact with generated superoxide (O₂⁻). When TBA⁺ is in larger concentrations, and large reductive overpotentials are applied, a quasi-reversible OER peak emerges with repeated cycling (characteristic of formulations without Ca²⁺ cations). In situ Raman microscopy and rotating ring-disc electrode (RRDE) experiments revealed more about the nature of species formed at the electrode surface and indicated the progressive evolution of a charge storage mechanism based upon trapped interfacial redox. The first electrochemical step involves generation of O₂⁻, followed primarily by partial passivation of the surface by Ca_xO_y product formation (the dominant initial reaction). Once this product matrix develops, the subsequent formation of TBA⁺--O₂⁻ is contained within the Ca_xO_y product interlayer at the electrode surface and, consequently, undergoes a facile oxidation reaction to regenerate O₂.

An interlayer product of oxygen reduction with Ca²⁺/TBA⁺ yields a quasi-reversible oxygen evolution reaction by inducing a trapped interfacial redox process.     

Four‐ and Five‐Coordinate Gallium Complexes Stabilized by Bidentate 2‐(Dimethylaminomethyl)Pyrrole Ligand: Molecular Structures of Ga[NC4H3(CH2NMe2)‐2]3 and GaMe2[NC4H3(CH2NMe2)‐2]

Treatment of GaCl₃ with one equiv of Li[NC₄H₃(CH₂NMe₂)‐2] (n = 1, 2, 3) in diethyl ether at ?78 °C yields GaCl_3‐n[NC₄H₃(CH₂NMe₂)‐2]_n (n = 1, 1 ; n = 2, 2 ; n = 3, 3 ). Compound 1 reacts with two equiv of RLi to afford GaR₂[NC₄H₃(CH₂NMe₂)‐2] ( 4a, R=Me; 4b, R=Bu ) via transmetallation. Reacting 2 with one equiv of RLi in diethyl ether, 3 and 4 are formed via ligand redistribution. Variable temperature ¹H NMR spectroscopic experiments reveal that the five‐coordinate gallium compound 3 is fluxional and results in a coalescence temperature at 5 °C, at which ΔG^≠ is calculated at ca. 10.4 Kcal/mole. All the new compounds have been characterized by ¹H and ¹³C NMR spectroscopy and the structures of compounds 3 and 4a have also been determined by X‐ray crystallography.     

Insertion Reactions of Carbon Disulfide into Mg‐C and Mg‐N Bonds: Syntheses and Structural Determinations of Mg(S2CY)2(THF)n(Y=NEt2, NiPr2, iPr,Ph) and BrMg(S2CZ)(THF)3(Z=Ph,iPr)

The insertion reaction of CS₂ with Mg(NR₂)₂ (R= Et, ⁱPr), MgR′₂ (R′= Et, Ph) and R″MgBr (R″= ⁱPr, Ph) respectively lead solid products, Mg(S₂CNR₂)₂(THF)_n ( 1 : R= Et, n=2; 2 : R= ⁱPr, n=1), Mg(S₂C′R)₂(THF)₂ ( 3 : ′R= Et, 4 : ′R= Ph), BrMg(S₂C″R) (THF)₃ ( 5 : ″R= ⁱPr, 6 : ″R= Ph) in which the inserted carbon disulfides act as terminal chelating ligands. These compounds were characterized with ¹H, ¹³C NMR, IR spectroscopy, mass spectrometry, elemental analyses, and X‐ray crystallography.     

NSLS Marks Silver Anniversary

November 22, 2007, marked the 25^th anniversary of the National Synchrotron Light Source's (NSLS) dedication. During the last quarter-century, Brookhaven National Laboratory's NSLS has made significant contributions to the field of synchrotron radiation, ranging from the Chasman-Green Lattice, novel insertion devices, and free electron laser research, to the development of numerous synchrotron experimental techniques and instrumentation.     

Using “Threading Followed by Shrinking” to Synthesize Highly Stable Dialkylammonium‐Ion‐Based Rotaxanes

Herein, we report a “threading followed by shrinking” approach for the synthesis of rotaxanes by using an “oxygen‐deficient” macrocycle that contained two arylmethyl sulfone units and the dumbbell‐shaped salt bis(3,5‐dimethylbenzyl)ammonium tetrakis(3,5‐trifluoromethylphenyl)borate as the host and guest components, respectively. The extrusion of SO₂ from both of the arylmethyl sulfone units of the macrocyclic component in the corresponding [2]pseudorotaxane resulted in a [2]rotaxane that was sufficiently stable to maintain its molecular integrity in CD₃SOCD₃ at 393 K for at least 5 h.