WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Conference Object Native and Light Induced Defect States in Wide Band Gap Hydrogenated Amorphous Silicon-Carbon (a-Si1 : H) Alloy Thin Films(Springer, 1997) Güneş, MehmetIn this study, wide band gap a-Si1-x C-x:H alloy thin films prepared with and without hydrogen diluation of (SiH4, CH4) were characterized using optical absorption, dark conductivity, steady-state photoconductivity, sub-bandgap absorption obtained with both photothermal deflection spectroscopy (PDS) and dual beam photoconductivity (DBP), and electron spin resonance (ESR) techniques. Experimental results of steady-state photoconductivity and sub-bandgap absorption for different generation rates were analyzed using a detailed numerical model based on Simmons-Taylor statistics. The densities, energy location and nature of the native and light induced defect states in diluted and undiluted a-Si1-xCx:H alloy thin films were derived from the best fits to the experimental data. The extracted parameters for defect states were compared with those of a-Si:H films both in the annealed and light degraded states.Article Citation - WoS: 15Citation - Scopus: 141/F-noise Study of Undoped Intrinsic Hydrogenated Amorphous Silicon Thin Films(American Physical Society, 1999) Güneş, Mehmet; Johanson, Robert E.; Kasap, Safa O.Conductance fluctuations in four samples of undoped intrinsic hydrogenated amorphous silicon (a-Si:H) were measured in the temperature range of 450 K to 500 K and for frequencies from 2 Hz to 3 kHz. The noise spectra divide into two regions that each fit a 1/fα power law but with different slope parameters α and different temperature dependences. At low frequencies, α is greater than unity and increases with temperature. At high frequencies, α is near 0.6 and temperature independent, but the noise magnitude decreases rapidly with temperature. We infer from the different dependences on temperature that the noise is generated by two independent mechanisms operating simultaneously in a-Si:H. We also observe that the 1/f noise exhibits a quadratic dependence on bias current and Gaussian statistics.Article Citation - WoS: 1Citation - Scopus: 4Synthesis and Characterization of a New Mono-Molybdenated Metallo-Ligand [mo{hb(3,5-Me2c3hn2)3}(no)cl(oc 6h4pph2-P)](Marcel Dekker Inc., 1999) Topaloğlu, Işıl; McCleverty, Jon A.The "metallo-ligands" can be considered effectively as a modified triphenylphosphine ligand, and used to generate novel transtion metal complexes in which electron-transfer and magnetism is embedded within the stable ligand framework. A new mono-molybdenated metallo-ligand was synthesized and characterized by NMR (1H and 31P-{1H}), IR and mass spectroscopy techniques as a starting material in the search for designing novel bimetallic complexes exhibiting optoelectronic properties and development of non-linear optical materials that possess commercial device applications.Article Citation - WoS: 29Citation - Scopus: 33Areally-Averaged Overland Flow Equations at Hillslope Scale(Taylor and Francis Ltd., 1998) Tayfur, Gökmen; Kavvas, M. LeventMicroscale-averaged inter-rill area sheet flow and rill flow equations (Tayfur and Kavvas, 1994) are averaged along the inter-rill area length and rill length to obtain local areally-averaged inter-rill area sheet flow and rill flow equations (local-scale areal averaging). In this averaging, the local areally-averaged flow depths are related to the microscale-averaged flow depths at the outlet sections (downstream ends) of a rill and an inter-rill area by the assumption that the flow in these sections has the profile of a sine function. The resulting local areally-averaged flow equations become time dependent only. To minimize computational efforts and economize on the number of model parameters, local areally-averaged flow equations are then averaged over a whole hillslope section (hillslope-scale areal averaging). The expectations of the terms containing more than one variable are obtained by the method of regular perturbation. Comparison of model results with observed data is satisfactory. The comparison of the model results with those of previously developed models which use point-scale and large-scale (transectionally) averaged technology indicates the superiority of this model over them. Microscale-averaged inter-rill area sheet flow and rill flow equations (Tayfur & Kavvas, 1994) are averaged along the inter-rill area length and rill length to obtain local areally-averaged inter-rill area sheet flow and rill flow equations (local-scale areal averaging). In this averaging, the local areally-averaged flow depths are related to the microscale-averaged flow depths at the outlet sections (downstream ends) of a rill and an inter-rill area by the assumption that the flow in these sections has the profile of a sine function. The resulting local areally-averaged flow equations become time dependent only. To minimize computational efforts and economize on the number of model parameters, local areally-averaged flow equations are then averaged over a whole hillslope section (hillslope-scale areal averaging). The expectations of the terms containing more than one variable are obtained by the method of regular perturbation. Comparison of model results with observed data is satisfactory. The comparison of the model results with those of previously developed models which use point-scale and large-scale (transectionally) averaged technology indicates the superiority of this model over themArticle Citation - WoS: 1Citation - Scopus: 2Synthesis and Characterization of Amido and Amido(monoalkylamido)nitrosyl-[tris(3,5 Complexes(Marcel Dekker Inc., 1997) Topaloğlu, Işıl; McCleverty, Jon A.The chloro-amido complex [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl(NH 2)] was prepared by treating [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl 2] with an excess of ammonia. The monoalkylamido complexes [Mo{HB(3,5-Me2C3HN2)3}-(NO)(NH 2)(NHR)] (R = Me, Et, Pr-n and Bu-n) were obtained by the reaction of [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl(NH 2)] with the appropriate primary amines. The IR and 1H NMR spectra of the new complexes were investigated.Article Citation - WoS: 4Citation - Scopus: 4Synthesis, Characterization and Reactivity of [exo-Nido 9h10me2)](Marcel Dekker Inc., 1996) Topaloğlu, IşılIn this work, the reaction of the 16-electron species [Rh(η3-C8H13)-(η5-C 2B9H9Me2)] with PPh3 was investigated and the product, [exo-nido-Rh-(PPh3)2(η5-C2B 9H10Me2)], which is in an equilibrium with the closo analogue was characterized by 31p{1H}, 1H, 13C and 11B NMR spectroscopy. A mechanism for the complex formation is suggested which is related to the previously reported reactions between the 16-electron complex and PR3 (R = Me and Et) ligands.Article Citation - WoS: 75Citation - Scopus: 82Body Waves in Poroelastic Media Saturated by Two Immiscible Fluids(John Wiley and Sons Inc., 1996) Tuncay, Kağan; Çorapçıoğlu, M. YavuzA study of body waves in elastic porous media saturated by two immiscible Newtonian fluids is presented. We analytically show the existence of three compressional waves and one rotational wave in an infinite porous medium. The first and second compressional waves are analogous to the fast and slow compressional waves in Biot's theory. The third compressional wave is associated with the pressure difference between the fluid phases and dependent on the slope of capillary pressure-saturation relation. Effect of a second fluid phase on the fast and slow waves is numerically investigated for Massillon sandstone saturated by air and water phases. A peak in the attenuation of the first and second compressional waves is observed at high water saturations. Both the first and second compressional waves exhibit a drop in the phase velocity in the presence of air. The results are compared with the experimental data available in the literature. Although the phase velocity of the first compressional and rotational waves are well predicted by the theory, there is a discrepancy between the experimental and theoretical values of attenuation coefficients. The causes of discrepancy are explained based on experimental observations of other researchers.Conference Object Progress Depends on Unbalance and Disorder(Institute of Electrical and Electronics Engineers Inc., 1997) Özcan, A. CanTechnology is a state of progress which depends on unbalanced structures of human functions and relations. Technology was once the vital element of mankind to survive in nature. But today, technology has reached a perfection level above any natural entity including homo technologicus. Thus, the natural selection has become the technological selection, and technology which was once a servant for mankind, has become the master. An attitude towards life which does not depend on ethical, logical or aesthetic principles only brings high technology to the wealthy and the powerful, discriminating the rest including nature itself.Article Adsorption Equilibrium and Dynamics of Lactase/Cm-sephadex System(Kluwer Academic Publishers, 1995) Harsa, Hayriye Şebnem; Göksungur, Yekta; Güvenç, UlgarPartitioning behaviour and adsorption isotherms of lactase/CM-Sephadex system at equilibrium were investigated together with the adsorption kinetics in this study. Maximum adsorption was obtained at the pH values between 5.5–6.0. Adsorption isotherm was a close fit to the Langmuir model.