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Articles 61 - 74 of 74
Full-Text Articles in Physical Sciences and Mathematics
A Glancing Incidence Exafs Study Of Evaporated Silver Films On Glass, Ahmet Bulut, Bünyami̇n Karabulut, Engi̇n Başaran, James Robinson
A Glancing Incidence Exafs Study Of Evaporated Silver Films On Glass, Ahmet Bulut, Bünyami̇n Karabulut, Engi̇n Başaran, James Robinson
Turkish Journal of Physics
A glancing incidence EXAFS experiment has been carried out with evaporated silver films on glass substrates. Prior to EXAFS data collection, a reflectivity curve was performed from which the critical angle for total external reflection of x-rays from surface were determined. The analysed EXAFS data revealed that there is a reduction in the coordination number and an increase in Debye-Waller factor compared to bulk values. These changes were explained in terms of grain size effect and the surface effects of the silver film.
The Effect Of Potassium Doping On Resistive Transitions And Transport Critical Current Of Bulk Ybco High-Tc Superconductors, S. Çelebi̇, A. Öztürk, İ. Karaca, U. Kölemen
The Effect Of Potassium Doping On Resistive Transitions And Transport Critical Current Of Bulk Ybco High-Tc Superconductors, S. Çelebi̇, A. Öztürk, İ. Karaca, U. Kölemen
Turkish Journal of Physics
We report on observations of the effect of potassium in YBCO (123) high temperature superconductors with nominal composition Y\( _{1-0,2x} \) Ba\( _{2-0.2x} \) K\( _{x} \) Cu\( _{3} \) O\( _{y} \). The electrical resistivity measurements show that the critical temperature T$_{c} \) (R=0) shifted slightly to lower temparature due to the K doping process. This process also decreases the transport critical current density and the activation energy for thermally activated flux flow. The magnetic field dependence of \( j_{c} \) was measured at 77 K after zero field cooling (ZFC) when the applied magnetic field is impressed (ZFCV) …
Internal Photoemission Spectroscopy For A Ptsi/P-Si Schottky Junction, Bülent Aslan, Raşi̇t Turan
Internal Photoemission Spectroscopy For A Ptsi/P-Si Schottky Junction, Bülent Aslan, Raşi̇t Turan
Turkish Journal of Physics
Properties of internal photoemission in a PtSi-Si Schottky junction have been studied. The traditional Fowler plot of a detector's photoyield is found to be nonlinear for values close to the barrier height of the junction. It is shown that the model that takes all scattering mechanisms into account provides a successful description for the experimental results. It is also shown that the photoemission spectrum is independent of temperature in agreement with this model. The properties of detector's ambient influence the photoemission spectrum for wavelength of 3 $\mu$m or less. A strong loss in the detector's response is observed at around …
^{87}Rb Nmr Relaxation And Vortex Dynamics In Rb_3c_{60}, Fügen Tabak, Maurizio Corti̇
^{87}Rb Nmr Relaxation And Vortex Dynamics In Rb_3c_{60}, Fügen Tabak, Maurizio Corti̇
Turkish Journal of Physics
^{87}Rb NMR relaxation measurements in superconducting fullerene Rb_{3}C_{60} for various values of the external field are reported. In the normal state the results are in agreement with T_{1}T= Constant. Below T_{c}, while no evidence of Hebel-Slichter peak is present in temperature dependence of T_{1}^{-1} , maxima are observed in \( T_{2}^{-1} at T=22K characteristic of vortex field fluctuation. T_{1} shows an anomalous field dependence not yet explained.
Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak
Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak
Turkish Journal of Physics
The second order contribution for the relativistic scattering of massless spin-$\frac{1}{2}$ particles from an infinitely long solenoid, in the context of covariant perturbation theory, is calculated and shown to vanish. Thus, Born approximation is consistent for this case as well.
Interaction Between Cesium Chloride Molecules And Metal Atoms Under Coadsorption On A Single Graphite Layer On Iridium, N. M. Nasrullaev
Interaction Between Cesium Chloride Molecules And Metal Atoms Under Coadsorption On A Single Graphite Layer On Iridium, N. M. Nasrullaev
Turkish Journal of Physics
Using the method of continuos flow to investigate the kinetics of reaction between atoms and molecules, the efficiency of substitution reactions (K, Na, Li)+ CsCl is shown to decrease. The efficiency is found to strongly depend on temperature tending to saturation with decreasing temperature. This fact is in accordance with Bonzel's concept.
The Effect Of Various Experimental Parameters On Glow Peaks And Trapping Parameters Of Caf_2:Dy (Tld-200) Crystals, A. Necmeddi̇n Yazici, M. Yakup Hacii̇brahi̇moğlu, Meti̇n Bedi̇r
The Effect Of Various Experimental Parameters On Glow Peaks And Trapping Parameters Of Caf_2:Dy (Tld-200) Crystals, A. Necmeddi̇n Yazici, M. Yakup Hacii̇brahi̇moğlu, Meti̇n Bedi̇r
Turkish Journal of Physics
In the present study, thermoluminescence glow curves of CaF$_{2}$:Dy (TLD-200) crystals have been investigated in detail between the temperature region 300-550 K. The number of peaks and their trapping parameters (E, s and b) have been determined using the computerized glow curve fitting, peak shape and isothermal decay methods. In addition, the effect of storage times at room temperature, dose levels and heating rates on the trapping parameters have been investigated in detail by using computerized glow curve deconvolution method (CGCD) using first and general order kinetic equations.
Optical Properties Of Zns Thin Films, M. Y. Nadeem, Waqas Ahmed
Optical Properties Of Zns Thin Films, M. Y. Nadeem, Waqas Ahmed
Turkish Journal of Physics
Zinc sulfide (ZnS) thin films of different thickness were deposited on Corning 7059 glass substrate at room temperature and high vacuum using resistive heating technique. The film properties investigated include their absorbance / transmittance / reflectance spectra, band gap, refractive index, extinction coefficient, optical conductivity, complex dielectric constant and thickness. The films were found to exhibit high transmittance (60-99\%), low absorbance and low reflectance in the visible / near infrared region up to 1100 nm. However, the absorbance of the films was found to be high in the ultra violet region with peak around 360 nm. The thickness (using quartz …
Thermal Stability Of Fe_{85.5}B_{14.5} Metallic Glass, Asghari Maqsood, Ashfaq Ahmad
Thermal Stability Of Fe_{85.5}B_{14.5} Metallic Glass, Asghari Maqsood, Ashfaq Ahmad
Turkish Journal of Physics
The thermal stability and crystallization behaviour of metallic glass Fe\( _{85.5} \)B\( _{14.5} \) were investigated by Dynamic Temperature Resistivity Measurement (DTRM) technique from room temperature to 1050K in forward and reverse mode at a heating rate of 40 K/hr. The slope of Resistivity-Temperature-Curve (RTC) changes sign and magnitude at the temperature where the transition takes place. Differential Thermal Analysis (DTA) was carried out at the heating rates of 10, 20, 30 \& 40 K/min. A comparison of the results of DTRM and DTA measurements shows that crystallization in this alloy is two-stage process. Activation energy for two crystallization steps …
The Magnetic Super-Exchange Coupling In Copper(Ii) Acetate Monohydrate And A Redetermination Of The Crystal Structure, Ayhan Elmali
The Magnetic Super-Exchange Coupling In Copper(Ii) Acetate Monohydrate And A Redetermination Of The Crystal Structure, Ayhan Elmali
Turkish Journal of Physics
The magnetic properties and redetermination of crystal structure of copper(II) acetate monohydrate have been studied. The copper(II) centers are separated by 2.617(1) \AA \ and antiferromagnetically coupled (-2J = 292.2 cm$^{-1}$), which follows from temperature-dependent magnetic susceptibility measurements in the temperature range 4.2 to 300 K. The magnetic moment at 300 K is about 2.1 Bohr magnetons while 0.1 Bohr magnetons at 4.2 K. The magnetic susceptibility is at a maximum near 250 K and decreases rapidly as the temperature is lowered to liquid helium temperature.
Barrier Heights Of Antimony / And Bismuth / P -Silcon (100) Junctions, A. A. Oberafo, A. Z. Ziriki
Barrier Heights Of Antimony / And Bismuth / P -Silcon (100) Junctions, A. A. Oberafo, A. Z. Ziriki
Turkish Journal of Physics
Junctions were fabricated in vacuum of about $10^{-5}$ Torr by thermal evaporation of Sb or Bi onto chemically etched $p$-type silicon (100) substrates. The electrical properties were studied by current voltage (I-V) measurements. Some of the Sb and Bi junctions were heated-treated for $\frac{1}{2}$ hr at 200 and 150^oC, respectively. The barrier height (BH) was equal to 0.64 eV for both as-deposited and heat-treated Sb junctions, while it was 0.56 and 0.74 eV for as-deposited and heat-treated Bi Junctions, respectively. These observatimons indicate that for Sb junctions, annealing at a temperature of 200^oC resulted only in partial elimination of any …
Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik
Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik
Turkish Journal of Physics
The normal reflectance of single crystal Si was measured at 0.5 5.6 eV range by unpolarized light. Optical parameters of Si were determined from this reflectance data by using two different methods: oscillator fit procedure and Kramers-Kronig analysis. The refractive index, extinction coefficient and the real and imaginary parts of complex dielectric constant obtained by these two methods were compared. A good agreement was found between two methods. Furthermore, the optical parameters so obtained seem to be in a satisfactory agreement with the literature.
Linac-Ring Type \Phi Factory Of Basic And Applied Research, A. Kenan Çi̇ftçi̇, Osman Gürkan, Turan Olgar, Erdal Recepoğlu, Saleh Sultansoy, Ömer Yavaş, Meti̇n Yilmaz
Linac-Ring Type \Phi Factory Of Basic And Applied Research, A. Kenan Çi̇ftçi̇, Osman Gürkan, Turan Olgar, Erdal Recepoğlu, Saleh Sultansoy, Ömer Yavaş, Meti̇n Yilmaz
Turkish Journal of Physics
In this paper, main parameters for linac-ring type collider designed for producing $\phi $ particles copiously are estimated and the potential of this machine in particle physics research is investigated. Moreover, parameters for free electron laser and synchrotron radiation obtained from electron linac and positron ring, respectively, are determined and applications of these radiations are summarized.
A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten
A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten
Turkish Journal of Physics
Product operator formalism is widely used for analytical description of multiple-pulse NMR experiments for weakly coupled spin systems. 3D J-resolved NMR spectroscopy is widely used in order to resolve the chemical shift along one axis and spin-spin coupling parameters along the two other axis. In this study, product operator theory is used for analytical description of heteronuclear 3D J-resolved NMR spectroscopy for the \( IS_nK_m (I=1/2, S=1/2, K=1/2; n=1,2, m=1,2,3) \) spin system.