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Molecular oxygen adsorbed on (110) and polycrystalline Cu surfaces has been investigated by UPS, XPS, AES, HREELS and LEED. Molecularly adsorbed O2 on the (110) surface shows the characteristic three-peak He II spectrum due to πg, πu and σg orbitals, accompanied by an O-O stretching frequency at 660 cm−1. On the polycrystalline Cu surface, adsorbed O2 shows the three peak He II spectra with a considerably smaller separation between the πu and σg band and two O-O stretching bands at 610 and 880 cm−1. O2 adsorbed on the Cu(110) surface gives rise to a (1 × 1) LEED pattern and characteristic K π∗π∗ transition in the Auger spectrum.
Measurement of the chemical shifts ΔE of the K-absorption edge in both crystalline and amorphous states of several solids shows that ΔE is generally smaller in the amorphous state. More covalent solids appear to be associated with small values of ΔE.
The discovery of graphene marks a major event in the physics and chemistry of materials. The amazing properties of this two-dimensional (2D) material have prompted research on other 2D layered materials, of which layered transition metal dichalcogenides (TMDCs) are important members. Single-layer and few-layer TMDCs have been synthesized and characterized. They possess a wide range of properties many of which have not been known hitherto. A typical example of such materials is MoS 2 . In this article, we briefly present various aspects of layered analogues of graphene as exemplified by TMDCs. The discussion includes not only synthesis and characterization, but also various properties and phenomena exhibited by the TMDCs. This article is part of the themed issue ‘Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene’.
All the vibrational frequencies of the (α - x) and (β - x) excited states of HCN and DCN as well as the 1 Au states of C2H2 and C2D2 have been calculated. Based on the calculated frequencies, thermodynamic properties of the excited states have been evaluated.
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The ultra-violet absorption spectra of isomeric substituted phenyl amino-1,2,3-triazoles have been studied. The influence of the substituents in the 1-, 4-, and 5-positions is discussed. The spectra of these triazoles have been of significant use for analytical and structural studies in this heterocyclic system.
The 2p core-level binding energies of Cu and Ni clusters increase while the kinetic energies of the LMM Auger lines decrease with decreasing cluster size. The shifts in the core-level binding energy and the Auger kinetic energy relative to the bulk metal are largest in the case of clusters deposited on an insulating substrate such as Al2O3 and least on amorphous carbon; shifts on TiO2 are intermediate between those on Al2O3 and carbon. The increase in core-level binding energies with decreasing cluster size signifies a metal to non-metal transition. The occurrence of such a transition is borne out more vividly by BIS studies. Accordingly, BIS studies on Pd clusters deposited on amorphous carbon clearly show that electron states are progressively introduced near the Fermi level with increase in cluster size. The chemical reactivity of transition-metal clusters varies with the size. Thus, the relative proportion of the atomic oxygen species increases with decreasing size of Ag clusters.
Three-dimensional homoleptic (single type of ligand) lead dicarboxylates with hybrid structures involving Pb–O–Pb linkages of the compositions, Pb(C5H6O4), I, and Pb(C6H8O4), II and III, have been synthesized and characterized. Three-dimensional heteroleptic (mixed ligands) lead dicarboxylates of the formulae, Pb2(C2O4)(C4H4O4), IV and Pb2(C2O4)(C6H8O4), V, with hybrid structures involving Pb–O–Pb linkages have also been prepared and characterized along with a novel two-dimensional lead nitrate-oxalate of the composition, (OPb2)2(C2O4)(NO3)2, VI. In all these dicarboxylates, there is two-dimensional inorganic connectivity and the lead (II) cation has hemi- or holo-directed coordination geometry. Depending upon the torsional angle and the coordination mode of the dicarboxylate anions as well as the geometry of the lead (II) cations, these hybrid compounds exhibit two types of two-dimensional inorganic connectivities.
Hopping conduction in Ln 1-x Sr x CoO 3 is discussed in terms of localization due to disorder and in the light of mossbauer measurements. The hopping times deduced from conductivity and mossbauer effect differ widely, and an explanation is suggested.
This article is written to draw the attention of chemists and departments of chemistry to the discipline of clinical chemistry as deserving attention in undergraduate and postgraduate education and in its career possibilities for chemistry graduates. The authors suggest that chemistry departments might profitably consider, in their teaching programs, the inclusion of some elements of clinical chemistry.
