Although the theory of photoemission from single-crystalline solids and ordered overlayers has been studied by almost every available theoretical tool, it is quite surprising that there has not yet been any theoretical investigation of photoemission from the disordered condensed…
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Zn₁₋xMnxS is a ternary semiconductor compound which belongs to the family of diluted magnetic semiconductors (DMS). It has two crystalline phases: cubic for x ≤ 0.10, and hexagonal for 0.10 ≤ x ≤ 0.50. Its energy gap is temperature and x dependent. The gap, ranging from 3.7 to 3…
Superconductor samples of YBa\sb2Cu\sb3O₇₋x were prepared by two different methods. Measurements using XRD, SEM, EPMA, and four probe method indicated single phased samples with orthorhombic structure and transition temperature of 92 K. Samples were further studied by XPS and UP…
We calculated the dielectronic recombination and resonance excitation cross sections and rate coefficients of Al-like S³⁺ ion at low energies (ec < 1.22 Ry) for the process in which 3s electron of the ground state (3s\sp2 3p)\sp2P is excited to the 3p level of the first excited …
The optical properties of the diluted magnetic semiconductor Zn₁₋xMnxS have been studied by using photoluminescence emission, lifetime and excitation spectroscopies. In photoluminescence spectroscopy three bands were found peaking at 585 nm (yellow band), 650 nm (orange band) an…
Scope of Study. Thermoluminescence (TSL) was monitored in swept and unswept high quality synthetic quartz by irradiating at 96K with a high energy (1.5 MeV) electron-beam and recording the luminescence output as the temperature was increased from that temperature to 273K. Simult…
In this thesis, a group-theoretical analysis of the characteristic modes of lattice vibrations for ZnWO\sb4 single crystals is given. The assignments of the vibrational modes have been made. The temperature dependence of the Raman spectra, which is reported here for the first ti…
The effect of different amounts of copper on the optical properties of Cux(Ge₀.₉₅Sn₀.₀₅Se\sb2)₁₋x flash-evaporated glassy films was studied. The copper content x of the alloy glasses was varied from 0 to 0.30. It is found that the photodarkening in Cux(Ge₀.₉₅Sn₀.₀₅Se\sb2)₁₋x is …
The electronic structures of the II-VI semiconductors in the Wurtzite structure (ZnO, ZnS, ZnSe, CdS, and CdSe) were calculated within the local-density approximation (LDA) using the linear muffin-tin orbitals (LMTO) method. The cation d states were included in the valence band.…
Fe-substituted Y123 and Bi-based high Tc superconducting samples were prepared and studied. Magnetic susceptibility measurements, x-ray diffraction and Scanning Electron Microscopy were used to study the transition temperature Tc, preferential grain orientation and phase formati…
The objectives of the present thesis were mainly directed towards the development of new preparative procedures, rather than to prepare altogether new high-Tc materials, and to study the effects of compositional variations using measurements such as X-ray Powder Diffraction (XRD…
This dissertation presents an experimental study of hydrogen bonding in the solid hydrogen halides under high pressure. The high pressures were obtained with a diamond-anvil high pressure cell. Raman scattering experiments were performed on hydrogen bromide and hydrogen fluoride…
Scope and method of study. The objective of this study is to investigate the point defects in a series of LiNbO\sb3 crystals which are either undoped, co-doped with magnesium and iron, or titanium doped. Electron spin resonance (ESR), electron nuclear double resonance (ENDOR), a…
Light scattering studies of the melting transition in phenyl salicylic acid commonly known as salol have been performed. Using a 5145(ANGSTROM) argon ion laser, both Brillouin and Raman scattering experiments on salol were performed very close to the melting point and down to ro…
Scope and Method of Study. Time-resolved site-selection spectroscopy is utilized to study spectral energy migration between Eu('2+) ions in RbMgF(,3):Euk('2+),Mn('2+) crystal. Degenerate four-wave mixing (FWM) transient-grating spectroscopy is employed to study certain nonlinear…
Scope of Study. This study was concerned with the measurement of the thermal conductivities of three different synthetic quartz samples. Thermal conductivity measurements were taken for two samples, Electronic grade sample, EG-S, and Premium Q sample, PQ-S, on the range of 4.5 t…
An alternative method for the growth of crack free, dislocation reduced III-Nitride layers on Silicon substrate has been developed that relies on formation of an ion implanted defective layer in the substrate with implantation taking place in the presence of AlN buffer layer. Th…