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By making use of the fact that single‐ and few‐layer nanosheets of GaS and GaSe are readily obtained by micromechanical cleavage because of their mica‐like morphology, we were able to prepare GaN nanosheets by the reaction of these chalcogenide nanosheets with ammonia at 600–650 °C. The nitride nanosheets were characterized by transmission electron microscopy, atomic force microscopy, and other methods. Few‐layer VN was obtained by high‐temperature ammonolysis of exfoliated V 2 O 5 sheets. Ammonolysis of MoO 3 and MoS 2 nanosheets yields the nitride nanosheets.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Generation of H2 from water has emerged to be an important alternative for replacing fossil fuels. In this context, a variety of materials has been investigated as electrocatalysts or photocatalysts for the reduction of water. Of these, transition metal dichalcogenides have emerged to be effective catalysts yielding good hydrogen evolution activity. This is particularly true of photocatalysis. MoS2 in the form of nanosheets exhibits particularly good activity in its metallic form and also in covalently linked composites with C3N4 and such two-dimensional (2D) materials. In this article, we present both electrochemical and photochemical catalysis by 2D-transition metal dichalcogenides in the hydrogen evolution reaction.

No abstract is provided for this article.

Charge-transfer satellites due to eg → eg * and a1g → a1g * transitions have been observed for the first time next to the ligand core level peaks in the X-ray photoelectron spectra of metal chlorides and sulphides. These transitions are also seen next to the metal core levels in the case of the chlorides. Observation of these satellites, specially in the case of sulphides, underscores the crucial role of metal-ligand overlap in determining the intensity of charge-transfer satellites.

No abstract is provided for this article.

No abstract is provided for this article.

This text surveys the various aspects of the fundamental problem related to the metallic and non-metallic states of matter, a question physicists have been studying for almost 100 years. The book poses questions and challenges in this area, as well as highlighting present understandings of the topic. Topics covered by the book include physics of dense ionized metal plasmas; metallic hydrogen; pressure-induced metallization; the M-I transition in doped semiconductors; transport studies in doped semiconductors near the metal-insulator transition; new results in old oxides; metal-insulator transition in 3d transition metal perovskite oxides investigated by high-energy spectroscopies; alkali metal-alkali halide melts; hopping conductivity in granular metals revisited; superconductor-insulator transition in cuprates; molecular metals and superconductors; shear induced chemical reactivity; shear, co-ordination and metallization; quantum diffusion and decoherence; the Mott transition; recent results, more and surprises; Mott-Hubbard-Anderson models.

An experimental charge density study has been carried out on N‐H + …O − bonds in the proton‐transfer compound piperazinium oxalate as well as on the normal O‐H…N bonds in the thiodiglycolic acid‐4,4′‐bipyridine complex, based on X‐ray diffraction measurements at 130 K. The results are compared with those of the normal N‐H…O bonds in 5‐nitrouracil. In spite of the different crystal geometries, the N‐H + …O − and the N‐H…O bonds exhibit similar values of electron density and the associated curvatures at the hydrogen‐acceptor bond critical points (BCPs). Surprisingly, the polarization parameters of the two BCPs are comparable (˜20%). The pseudoatomic charge on the protonated N atom (in N‐H + …O − ) is, however, much smaller (‐0.05 e ) in comparison to the unprotonated case (˜ ‐0.2 e ). The O‐H…N hydrogen bonds exhibit shorter H…N distances compared to the charged and the uncharged H…O bonds. Accordingly, the electron densities and the curvatures evaluated at the H…N critical points are also much higher.

ESR spectra of three inorganic glasses doped with Mn2+ and Fe3+ have been studied through their glass transition temperatures (T g). Spectral features in each case have been discussed with reference to site symmetries. The intensity of the ESR signal has been bound to decrease in the region of T g. An attempt has been made to explain this interesting feature on the basis of a two-state model.

While C60 interacts with aromatic amines such as dimethylaniline in the ground state, C70 does not. Fluorescence spectroscopic studies, including lifetime measurements, show the formation of exciplexes of both C60 and C70 with aromatic amines in nonaromatic solvents such as methylcyclohexane. Exciplexes are however not formed in benzene solvent, due to π—π interaction between benzene and the fullerene. Based on spectroscopic absorption measurements, it is shown that both C60 and C70 do indeed interact with benzene in the ground state.

Evidence for the presence of holes on oxygen in the cuprate superconductors is critically examined. While there is little doubt that the O 2p holes are responsible for superconductivity, the available experimental evidence for the pairing of these holes does not appear to be altogether sufficient.