Browsing Department of Physics & Materials Science by Title
Now showing items 119-138 of 158
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Revisiting non-degenerate parametric down-conversion
(Springer-Verlag, 2008)he quantum dynamics of a two-mode non-resonant parametric down-conversion process is studied by recasting the time evolution equations for the basic operators in an equivalent spin equation form with simpler exact solutions ... -
Rheological Properties of Blends of Isotactic Polystyrene–Isotactic Poly(para-methylstyrene) Films Derived from a Comparative Dewetting Study
(American Chemical Society, 2020)We examined changes in rheological properties of nonequilibrated spin-coated thin films of isotactic polystyrene (iPS) and isotactic poly(para-methylstyrene) and blends thereof by dewetting experiments. For 200 nm thick ... -
Robust Arduino controlled spin coater using a novel and simple gravity chuck design
(Elsevier, 2023-06)Spin coaters offer an invaluable method of thin film fabrication. Various implementations, both proprietary and open-source exist, offering vacuum and gravity samples chucks. These implementations vary in their reliability, ... -
Role of bismuth and substrate temperature on the optical properties of some flash evaporated se100-x bix glassy system
(University of Nairobi, Kenya, 2015)Chalcogenide glasses are very important in the modern technology especially selenium-based. These glasses are sensitive to electromagnetic radiation useful in the infrared optics. The study investigated the effect of ... -
Role of oxygen concentrations on structural and optical properties of RF magnetron sputtered ZnO thin films
(Springer US, 2019)We report an investigation on the efect of oxygen fow rate on the structural and optical properties of zinc oxide thin flms prepared by RF magnetron sputtering. The structural measurements were carried using grazing ... -
SCINDA-GPS derived TEC depletions and amplitude scintillations over Kisumu, Kenya during selected quiet and storm days of 2013 and 2014
(International Journal of Advanced Astronomy, 2020)Total Electron Content (TEC) depletion and amplitude scintillation (S4) can be derived from, SCINDA-GPS receivers situated in various parts of the equatorial region. In this paper we present results of characterization ... -
Shell structure of the SU (N) generator spectrum: interpretation as spin angular momentum operators
(Research gate, 2020)We have established that SU(N) symmetry group generators occur in a spectrum with a quantum structure composed of N − 1 configuration shells each containing a definite number of symmetric and antisymmetric pairs of ... -
Similarity Transformation Analysis of Heat and Mass Transfer Effects on Steady Buoyancy Induced MHD Free Convection Flow Past an Inclined Surface
(2017)The present work is devoted to the problem of a steady two di- mensional hydromagnetic convective ow of a viscous, incompressible electrically conducting uid past an inclined semi-in nite plate in the presence of ... -
Solutions of second-order partial differential equations in two independent variables using method of characteristics
(nternational Journal of Engineering and Mathematical Sciences, 2013-06-01)In this paper we have classified second order linear PDEs into three types, hyperbolic, parabolic and elliptic. Hyperbolic equations have two distinct families of (real) characteristic curves, parabolic equations have a ... -
Some new features of photon statistics in a fully quantized parametric amplification process
(Scientific Research Publishing, 2014)An exact quantum treatment reveals that signal and idler photon number operators are not wellbehaved dynamical operators for studying photon statistics in parametric amplification/downconversion processes. Contrary to ... -
: Spray Pyrolysis Technique (SPT) was used to deposit thin films (TFs) of cadmium stannate, doped with iron (Fe) for the first time. The precursor solutions that were used wereprepared at a concentration of 0.1M, doped with Feand then sprayed onto the pre-heated glass slides immediately at deposition temperatures of 350 ± 7°C, 400 ± 7°C and 450 ± 7°C. The optical properties of the deposited Fe-doped TFs were studied in the wavelength range of 300-1100nm. The X-Ray diffraction (XRD) studies showed that the TFs were orthorhombic with growth orientation along the (2 0 0) direction. Film thickness of 85 ± 10 nm was obtained. It was found out that anincrease in the deposition temperature increased transmittance and band gap, but decreased absorption coefficient, extinction coefficient and refractive index, which was attributed to the improvement in crystallinity of the deposited TFs. Doping reduced transmittance and band gap, but increased refractive index, absorption coefficient and extinction coefficient, which was attributed to the increase in free carriers. KEYWORDS:cadmium stannate, deposition temperature, iron-doped, optical properties of cadmium stannate
(Elsevier, 2020)The elastic properties of the orthorhombic cadmium stannate (Cd2SnO4) were investigated using density functional theory, applying both energy-strain relationship (which is found in the literature) and stress-strain ... -
Stability Investigation in the Optical Properties of Thermally Evaporated Ge5Se95-x Znx Thin Films
(University of Nairobi, Kenya, 2015)Selenium-based chalcogenides are useful in telecommunication devices like infrared optics and threshold switching devices. The investigated system of Ge5Se95-xZnx (0.0 ≤ x ≤ 4 at.%) has been prepared from high purity ... -
Steady MHD poiseuille flow between two infinite parallel porous plates in an inclined magnetic field
(2012)In this paper, we examine the motion of a two dimensional steady flow of a viscous, electrically conducting, incompressible fluid flowing between two infinite parallel porous plates under the influence of transverse magnetic ... -
Structural and Mechanical Properties of NbN Alloyed with Hf, In, and Zr for Orthopedic Applications: A First-Principles Study
(MDPI, 2024-01-17)The search for biocompatible, non-toxic, and wear-resistant materials for orthopedic implant applications is on the rise. Different materials have been investigated for this purpose, some of which have proved successful. ... -
Structural and Mechanical Properties of theTi32Al68 and Ti40Al60 Binary Alloys: Experimental and computational Studies
(Elsevier, 2021)We studied aluminium-rich Ti-Al (Ti32Al68 and Ti40Al60) binary alloys that were composed of TiAl and TiAl2 lamellar microstructures. The law of mixtures was employed in calculating the theoretical Young’s moduli. The ... -
Structural and Optical Probe into Rare Earth Doped ZnO for Spectral Conversion in Solar Cells
(Jenny Stanford Publishing, 2022)This chapter examines the relationship between structure and optoelectronic properties of rare earth doped Zinc oxide (ZnO) thin films fabricated by RF magnetron sputtering for photovoltaic applications. A doped ZnO layer ... -
Structural and spectroscopic analysis of ex-situ annealed RF sputtered aluminium doped zinc oxide thin films
(AIP Publishing LLC, 2017)Aluminium doped zinc oxide thin films are prepared by Radio Frequency magnetron sputtering in pure argon atmosphere at 100 W. The structural results reveal good film adhesion on a silicon substrate (001). The thin films ... -
A study of the Equatorial Ionosphere over Nairobi During selected magnetically disturbed and quiet times for the year 2009 Using co-located instruments
(ARC, 2014)Investigation of the behavior of the Equatorial Ionosphere over Nairobi-Kenya within the East Africa region is done using co-located instruments, that is, SCINDA-GPS system and a Magnetometer ( MAGDAS). This was done for ... -
A study of the Equatorial Ionosphere over Nairobi During selected magnetically disturbed and quiet times for the year 2009 Using co-located instruments
(IJARPS, 2014)Investigation of the behavior of the Equatorial Ionosphere over Nairobi-Kenya within the East Africa region is done using co-located instruments, that is, SCINDA-GPS system and a Magnetometer ( MAGDAS). This was done for ...