Now showing items 1-20 of 3825

    • Sedimentation rates in the central lake constance determined with210Pb and137Cs 

      von Gunten, H. R.; Sturm, M.; Erten, H. N.; Rössler, E.; Wegmüller, F. (Birkhäuser-Verlag, 1987)
      Sediment cores from central Lake Constance were dated with210Pb and137Cs. A sedimentation rate of (0.11±0.02) g·cm-2·y-1 was determined with the210Pb method.137Cs measurements revealed sedimentation rates of (0.11±0.01) ...
    • Metallization of Silicon upon Potassium Adsorption 

      Çıracı, Salim; Batra, I. P. (1987)
      We report novel features of potassium deposition on a Si(111)-(2×1) surface as a function of coverage. The binding is ionic even at the saturation coverage without any overlayer metallization. Up to a threshold coverage, ...
    • Scanning-tunneling microscopy at small tip-to-surface distances 

      Çıracı, Salim; Batra, I. P. (1987)
      The scanning-tunneling microscopy (STM) of graphite at small tip-to-surface distances is investigated using the self-consistent-field pseudopotential method. We have calculated potential, charge density in the region between ...
    • Molecular-dynamics study of self-interstitials in silicon 

      Batra, I. P.; Abraham, F. F.; Çıracı, Salim (American Physical Society, 1987)
      Results of a molecular-dynamics computer simulation are presented for atomic relaxations and relaxation energies for self-interstitials in a silicon crystal. The Stillinger-Weber model potential containing two- and three-body ...
    • Long-range order and segregation in semiconductor superlattices 

      Çıracı, Salim; Batra, I. P. (1987)
      Results of self-consistent energy-minimization calculations provide strong evidence that the ordered phases in epitaxially grown Ga1-xAlxAs and strained Si1-xGex alloys are metastable, in the sense that segregation into ...
    • An isomorphism theorem for Dragilev spaces 

      Kocatepe, M. (Birkhäuser-Verlag, 1988)
      Necessary and sufficient conditions for an Ly(a, l)-space to be isomorphic to some Lg(b, m)-space have been found.
    • Sorption/desorption of Cs on clay and soil fractions from various regions of Turkey 

      Erten, H. N.; Aksoyoglu, S.; Göktürk, H. (Elsevier, 1988)
      The sorption desorption behaviour of Cs ion in the concentration region of 10−8 to 10−4 meqml−1 have been studied using clay and soil fractions from various regions of Turkey. The sorption curves for all the material studied ...
    • C∗-actions on Grassmann bundles and the cycle at infinity. 

      Sertöz, S. (Aarhus Universitet * Mathematica Scandinavica, 1988)
      We describe the Grassmann Graph construction of MacPherson in the analytic category using a C∗-action and the corresponding BialynickiBirula decomposition. It is shown that the cycle at infinity is analytic in the compact ...
    • Sorption of cesium and strontium on montmorillonite and kaolinite 

      Erten, H. N.; Aksoyoglu, S.; Hatipoglu, S.; Göktürk, H. (De Gruyter Oldenbourg, 1988)
      Sorption characteristics of Cs+ and Sr++on montmorillonite and kaolinite type clays and soil fractions from various regions of Turkey were studied using the batch method. 137Cs and 90Sr were used as tracers. Concentrations ...
    • Critical relaxation of the two-dimensional three-state Potts model with conserved dynamics 

      Aydın, M.; Yalabık, M. C. (Institute of Physics (Great Britain), 1988)
      The dynamical critical exponent z is obtained using the finite-size scaling method for the two-dimensional three-state Potts model with conserved dynamics. It is observed that there is a change in the dynamical behaviour ...
    • Efficiency calibration and summation effects in gamma-ray spectrometry 

      Erten, H. N.; Aksoyoğlu, S.; Göktürk, H. (Kluwer Academic Publishers, 1988)
      Precise, absolute γ-ray efficiences (∈γ) and total efficiences (∈T), have been measured at various distances from the detector, using a set of standards. The observed linear variation of ∈γ and ∈T as well as ∈γ/∈T with Eγ ...
    • Surface metallization of silicon by potassium adsorption on Si(001)-(2×1) 

      Çıracı, Salim; Batra, I. P. (American Physical Society, 1988)
      We present the detailed results of self-consistent and geometry-optimized total-energy, band-structure, and charge-density calculations for a potassium-covered Si(001)-(2×1) surface, and for an unsupported potassium ...
    • Effect of tip profile on atomic-force microscope images: a model study 

      Abraham, F. F.; Batra, I. P.; Çıracı, Salim (American Physical Society, 1988)
      Adopting the empirical silicon interatomic potential of Stillinger and Weber, we investigate the effect of the tip profile on the atomic-force microscope images for a prototype system, Si(001)-(2×1), and conclude that the ...
    • Electronic structure of strained Sin / Gen (001) superlattices 

      Çıracı, Salim; Gülseren, O.; Ellialtioğlu, Ş. (Pergamon Press, 1988)
      Using the empirical tight binding method we have investigated the electronic properties of the Sin/Gen(001) strained superlattices as a function of the superlattice periodicity and the band misfit. For n ≥ 4 we have found ...
    • Calculations of STM linescans-general formalism 

      Ellialtioğlu, Ş.; Çıracı, Salim; Batra, I. P. (Pergamon Press, 1988)
      We have developed a formalism for calculating the line scans of the scanning-tunneling microscopy from the realistic substrate and tip wave functions. The tip wave functions are calculated self-consistently by using a ...
    • Tip induced localized states in scanning tunneling microscopy 

      Tekman, E.; Çıracı, Salim (Institute of Physics Publishing Ltd., 1988)
      We have investigated the Scanning Tunneling Microscopy (STM) of graphite with varying tip-to-surface distance. Using an LCAO type approach we showed that at small separations states are localized between the tip and the ...
    • Delta-Doping in strained (Si) / (Ge) superlattices 

      Çıracı, Salim; Batra, I. P.; Tekman, E. (American Physical Society, 1988)
      We present a comparative study of the pseudomorphic (Si)6/(Ge)6 and -doped (Si)3(Sb)(Si)2/(Ge)6 superlattices using the self-consistent pseudopotential method. The strained (Si)6/(Ge)6 superlattice has the lowest conduction-band ...
    • Superficial deep-water sediments of the Eastern Marmara Basin 

      Evans, G.; Erten, H.; Alavi, S. N.; Von Gunten, H. R.; Ergin, M. (Springer-Verlag, 1989)
      Superficial sediments (top ∼ Im) of the Eastern Mediterranean Basin, Sea of Marmara, Turkey accumulated rapidly (0.087 ± 0.012 g/cm2 · y) by hemipelagic sedimentation with only limited amounts of gravity flow or bottom ...
    • A Monte Carlo study of the BNNNI model 

      Aydin, M.; Yalabik, M. C. (IOP Publishing, 1989)
      The biaxially next-nearest-neighbour Ising (BNNNI) model is studied using the Monte Carlo procedure. The structure factor is used to identify the possible phases of the system. At intermediate temperatures, evidence for ...
    • Sorption of barium on kaolinite, montmorillonite and chlorite 

      Eylem, C.; Erten, H. N.; Göktürk, H. (Royal Society of Chemistry, 1989)
      The sorption characteristics of the Ba2+ ion on kaolinite, montmorillonite and chloritetype clays were studied using the batch method. Barium-133 was used as a tracer. The Ba2+ ion concentrations ranged from 10-8 to 10-5 ...