Anjali Kshirsagar

Photophysical properties of ZnS nanoclusters

Optical measurements on ZnS nanoclusters have been carried out to investigate surface effects along with quantum size effects. ZnS nanocrystals have been synthesized in the range of 1.5–2.5 nm, using different chemical methods as well as electronic passivating procedures. The size of nanoparticles has been estimated from empirical pseudopotential calculations. We have obtained a significantly narrower size distribution of ZnS nanocrystals than reported in earlier published results. We observed band gap luminescence in mercaptoethanol capped ZnS nanocrystals. Effects of various defect levels on the luminescent behavior of ZnS nanoparticles have been examined

Thiophenol-capped ZnS quantum dots

Free‐standing, stable, single‐sized, and highly pure ZnS nanosize particles or quantum dots are synthesized using a chemical route. The dimension of the quantum dots as estimated from x‐ray diffraction was about 7 and 15 A. The optical band gap for these particles was 5.2 and 4.8 eV, respectively, as compared with the bulk energy gap of 3.8 eV. These results are compared with the effective mass approximation. The observations indicate that only particular‐sized stable particles can be synthesized which should have minimum energy configuration. X‐ray photoelectron spectroscopy was utilized for examining stoichiometry and purity of the sample.

Adsorption of molecular hydrogen and hydrogen sulfide on Au clusters

The authors present theoretical results describing the adsorption of H2 and H2S molecules on small neutral and cationic gold clusters (Au(n)((0/+1)), n=1-8) using density functional theory with the generalized gradient approximation. Lowest energy structures of the gold clusters along with their isomers are considered in the optimization process for molecular adsorption. The adsorption energies of H2S molecule on the cationic clusters are generally greater than those on the corresponding neutral clusters. These are also greater than the H2 adsorption energies on the corresponding cationic and neutral clusters. The adsorption energies for cationic clusters decrease with increasing cluster size. This fact is reflected in the elongations of the Au-S and Au-H bonds indicating weak adsorption as the cluster grows. In most cases, the geometry of the lowest energy gold cluster remains planar even after the adsorption. In addition, the adsorbed molecule gets adjusted such that its center of mass lies on the plane of the gold cluster. Study of the orbital charge density of the gold adsorbed H2S molecule reveals that conduction is possible through molecular orbitals other than the lowest unoccupied molecular orbital level. The dissociation of the cationic Au(n)SH2+ cluster into Au(n)S+ and H2 is preferred over the dissociation into Au(m)SH2+ and Au(n-m), where n=2-8 and m=1-(n-1). H2S adsorbed clusters with odd number of gold atoms are more stable than neighboring even n clusters.

Ab initio calculations of structural and electronic properties of CdTe clusters

We present results of a study of small stoichiometric

How cationic gold clusters respond to a single sulfur atom.

Cd_{n}Te_{n}

Electronic structure of diluted magnetic semiconductors Ga1-xMnxN and Ga1-xCrxN

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Momentum-space properties from coordinate-space electron density

1{\leq}n{\leq}6

Two-component density functional theory of positron binding to negative ions

) clusters and few medium sized non-stoichiometric

Full-potential LAPW calculation of electron momentum density and related properties of Li

Cd_{m}Te_{n}

Electron energy level engineering in Zn1−xCdxSe nanocrystals

[(