Mode theory of three-layer cylindrical waveguides and its application to aurum(Au)/polystyrene(PS)-coated terahertz hollow waveguides

In this paper, we present a generic mode theory for the three-layer cylindrical waveguides consisting of three arbitrary material mediums. Based on derived eigenvalue equations of the TE, TM, and hybrid modes, the mode conditions of metal/dielectric-coated terahertz hollow waveguides are extracted. In addition, we quantitatively describe both the effective refractive indexes and the loss characteristics of the aurum/polystyrene-coated terahertz hollow waveguides operating at the TE₀₁, TM₀₁, and HE₁₁ modes. It is indicated that the loss coefficient of the TE₀₁ mode can be much lower than that of the TM₀₁, and HE₁₁ modes, and, especially, can tend to that of the terahertz wave in air. So the TE₀₁ mode is very significant for the hollow waveguides in term of low loss propagating of the terahertz wave. We expect these results to enable a variety of new long-distance THz applications in sensing, detecting and communicating.     

Visible light mediated metal-free oxidative aromatization of 1,3,5-trisubstituted pyrazolines

The visible light mediated oxidation of 1,3,5-trisubstituted pyrazolines under metal-free conditions was developed. Various substituted pyrazolines were oxidized to pyrazoles by irradiation with visible light/sunlight. A plausible mechanism was proposed for the light mediated oxidation proceeding via formation of intermediates with electron rich C-3 positions and electron deficient C-5 positions. Correlation between the electronic effect induced by the aryl substituents and the rate of oxidation was studied by UV–vis spectroscopy. This correlation study supported the proposed mechanism. Electron withdrawing substituents at the 3-phenyl group and electron releasing substituents at the 5-phenyl group enhanced the rate of oxidation; whereas, electron donating substituents at the 3-phenyl group and electron withdrawing substituents at the 5-phenyl group reduced the rate.     

薄膜生长及界面结构的计算机模拟

本文对薄膜沉积的形核、生长过程,对同质外延、异质外延生长过程中的某些现象进行了研究。特别是对界面势、界面畸变、界面缺陷以及气相、液相外延生长膜的最后形状等进行了计算机模拟研究,利用已有的实验结果与本工作进行了对比和验证。     

Experimental evidence of structural transition from fcc to bulk bcc in nanophase metal clusters of (Fe)n, (Cr)n, (Mo)n and (W)n produced by CO2 laser multiphoton decomposition of metal carbonyls

We have produced nanophase metal clusters, (Fe)_n, (Cr)_n, (Mo)_n and (W)_n, by multiphoton decomposition of the corresponding metal carbonyls with a 10.6 μm CO₂ laser in the presence of Ar and SF₆. The size distribution was narrow and the average diameter was 6, 3.5, 2 and 1 nm for Fe, Cr, Mo and W clusters, respectively. The structure was found to be bcc for both Fe and Cr clusters, fcc for Mo clusters, and amorphous for W clusters (note that all the bulk metals have bcc structure). Considering the cluster sizes (9630, 1870, 230 and 30 for Fe, Cr, Mo and W clusters, respectively) estimated from their average diameters, it is likely that there exists a structural transition from fcc to bulk bcc with increasing cluster size in these metal clusters.     

1-Ethoxycarbonyl-3-ferrocenyl-propan-1,3-dion und Ferrocen-1,1'bis(2,4-dioxobutansäureethylester) als Liganden für Übergangsmetallionen. Kristallstruktur von Bis(1-ethoxycarbonyl-3-ferrocenyl-propan-1,3dionato)kupfer(II)

1-Ethoxycarbonyl-3-ferrocenyl-propane-1,3-dion and Ferrocene-1,1′bis(2,4-dioxobutanoic acid ethylester) as Ligands for Transition Metal Ions. Crystal Structure of Bis(1-ethoxycarbonyl-3-ferrocenyl-propane-1,3dionato)copper(II) The ligands 1-ethoxycarbonyl-3-ferrocenyl-propane-1,3-dion and ferrocene-1,1′-bis(2,4-dioxo-butanoic acid ethylester) have been prepared by reaction of acetylferrocene or 1,1′-diacetylferrocene and diethyl oxalate. They yield neutral chelates with Cu^II, Ni^II, Zn^II, Co^II, and Mn^II. The acid dissociation constants of the ligands and the stability constants of their metal complexes including Fe^II complexes are reported. The structure of bis(1-ethoxycarbonyl-3-ferrocenyl-propane-1,3-dionato)copper(II) was determined by X-ray structure analysis. A cis arrangement with a nearly square planar coordination sphere at the Cu atom is found.     

Surface diffusion of metal atoms on polymer substrates during physical vapour deposition

 The surface diffusion of physical-vapour-deposited metal atoms on thermoplastic polymer substrates was investigated. In accordance with the hypothesis of the “classical” atomistic diffusion model, diffusion coefficients are derived from a Monte Carlo simulation. Because the “classical” atomistic diffusion model neglects the desorption of the metal atoms, the absolute diffusion data obtained in our investigations should only be considered as rough estimates. It is more the intention of our work to present relative values in order to correlate the metal surface diffusion on polymer substrates with their physical states (morphologies and surface dynamics). As expected, the diffusivity of metal atoms is strongly influenced by the chemical affinity (“reactivity”) between the metal atoms and the polymer substrate. Furthermore, the diffusivity strongly depends on the physical state of the polymer substrate. On polymer surfaces above the glass-transition temperature the surface diffusivity of metal atoms is 1 order of magnitude higher than the diffusivity below the glass-transition temperature. Received: 9 April 1999/Accepted in revised form: 21 October 1999     

Synthesis and characterization of 2-phosphonoethanesulfonic acid and a barium-hydrogenphosphonatoethanesulfonate — BaH(O3P-C2H4-SO3)

Following the strategy of using polyfunctional phosphonic acids for the synthesis of new metal phosphonates, the organic linker molecule 2-phosphonoethanesulfonic acid, H₂O₃P-C₂H₄-SO₃H (1) (H₃L), was synthesized and characterized in detail. The acid was used in a high-throughput (HT) investigation of the system BaCl₂/H₃L/NaOH/H₂O. The HT experiments comprising 48 individual hydrothermal reactions were performed to systematically investigate the influence of pH of the starting mixture as well as the molar ratio Ba²⁺: H₃L. Only two reaction products were observed: small amounts of BaCO₃ under basic conditions and BaH(O₃P-C₂H₄-SO₃) (2). For compounds 1 and 2 the crystal structures were determined from single-crystal X-ray diffraction data (H₂O₃P-C₂H₄-SO₃H: trigonal, P3₂, a=814.58(1), c=861.20(2) pm, Z=3, R1=0.0254, wR₂=0.0758 for I>2σ(I); BaH(O₃P-C₂H₄-SO₃): orthorhombic, Ibam, a=953.39(19), b=855.55(17), c=867.82(17) pm, Z=4, R1=0.0162, wR₂=0.0417 for I>2σ(I)). The structure of H₃L (1) is stabilized exclusively by strong hydrogen bonds. Compound 2 is built up by chains of edge sharing BaO₈ polyhedra. These chains are connected to a three-dimensional network by the -CH₂CH₂- linker of the ligand. Thermogravimetric investigation of compound 2, as well as IR spectra of 1 and 2 are presented.     

Photo-Activated Circularly Polarized Luminescence Film Based on Aggregation-Induced Emission Copper(I) Cluster-Assembled Materials

In this study, a pair of chiral copper(I) cluster-assembled materials (R/S- 2 ) was prepared, exhibiting unique photo-response characteristics with a concentration-wavelength correlation property in DMSO solution. By the combination of R/S- 2 with a polymethyl methacrylate (PMMA) matrix, the first photo-activated circularly polarized luminescence (CPL) film was developed, the CPL signal (g_lum=9×10⁻³) of which could be induced by UV light irradiation. Moreover, the film exhibited a reversible photo-response and extremely good fatigue resistance. Mechanism study revealed that the photo-response properties of the R/S- 2 solution and film are attributed to the aggregation-induced emission (AIE) characteristics of R/S- 2 and a photo-induced deoxygenation process. This study enriches the types of luminescent cluster-assembled molecules and provides a new strategy for the construction of metal cluster-based stimuli-responsive composite materials.     

Enabling the Operation of Highly Compatible LiI-3-Hydroxypropionitrile Small-Molecule Solid-State Electrolytes in Lithium Metal Batteries via Stepped-Amorphization Strategy

Integrating the advantages of both inorganic ceramic and organic polymer solid-state electrolytes, small-molecule solid-state electrolytes represented by LiI-3-hydroxypropionitrile (LiI-HPN) inorganic–organic hybrid systems possess good interfacial compatibility and high modulus. However, their lack of intrinsic Li⁺ conduction ability hinders potential application in lithium metal batteries until now, despite containing LiI phase composition. Herein, inspired by evolution tendency of ionic conduction behaviors together with first-principles molecular dynamics simulations, we propose a stepped-amorphization strategy to break the Li⁺ conduction bottleneck of LiI-HPN. It involves three progressive steps of composition (LiI-content increasing), time (long-time standing), and temperature (high-temperature melting) regulations, to essentially construct a small-molecule-based composite solid-state electrolyte with intensified amorphous degree, which realizes efficient conversion from an I⁻ to Li⁺ conductor and improved conductivity. As a proof, the stepped-optimized LiI-HPN is successfully operated in lithium metal batteries cooperated with Li₄Ti₅O₁₂ cathode to deliver considerable compatibility and stability over 250 cycles. This work not only clarifies the ionic conduction mechanisms of LiI-HPN inorganic–organic hybrid systems, but also provides a reasonable strategy to broaden the application scenarios of highly compatible small-molecule solid-state electrolytes.     

An Unlocked Two-Dimensional Conductive Zn-MOF on Polymeric Carbon Nitride for Photocatalytic H2O2 Production

Developing highly efficient catalytic sites for O₂ reduction to H₂O₂, while ensuring the fast injection of energetic electrons into these sites, is crucial for artificial H₂O₂ photosynthesis but remains challenging. Herein, we report a strongly coupled hybrid photocatalyst comprising polymeric carbon nitride (CN) and a two-dimensional conductive Zn-containing metal–organic framework (Zn-MOF) (denoted as CN/Zn-MOF(lc)/400; lc, low crystallinity; 400, annealing temperature in °C), in which the catalytic capability of Zn-MOF(lc) for H₂O₂ production is unlocked by the annealing-induced effects. As revealed by experimental and theoretical calculation results, the Zn sites coordinated to four O (Zn-O₄) in Zn-MOF(lc) are thermally activated to a relatively electron-rich state due to the annealing-induced local structure shrinkage, which favors the formation of a key *OOH intermediate of 2e⁻ O₂ reduction on these sites. Moreover, the annealing treatment facilitates the photoelectron migration from the CN photocatalyst to the Zn-MOF(lc) catalytic unit. As a result, the optimized catalyst exhibits dramatically enhanced H₂O₂ production activity and excellent stability under visible light irradiation.