Browsing by Subject "Electron beams"
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Item Open Access Coulomb drag effect in parallel cylindrical quantum wires(Pergamon Press, 1996) Tanatar, BilalWe study the Coulomb drag rate for electrons in two parallel quantum wires. The double-quantum wire structure is modeled for a GaAs material with cylindrical wires having infinite potential barriers. The momentum transfer rate between the wires (Coulomb drag effect) is calculated as a function of temperature for several wire separation distances. We employ the full wave vector and frequency dependent random-phase approximation (RPA) at finite temperature to describe the effective interwire Coulomb interaction. We find that the drag rate at high temperatures (i.e., T ≥ EF/2) is dominated by the collective modes (plasmons) of the system similar to the case in double-well structures. Including the local-field effects in an approximate way we estimate the importance of intrawire correlations to be significant. Copyright © 1996 Published by Elsevier Science Ltd.Item Open Access Doping of 2-Cl-PANI/PVC films by exposure to UV, γ-rays and e-beams(Elsevier Sequoia SA, Lausanne, Switzerland, 2000) Sevil, U. A.; Güven, O.; Birer, Ö.; Süzer, Ş.2-Chloro-polyaniline (2-Cl-PANI) is chemically prepared in its non-conducting (Emeraldine Base, EB) form and dissolved together with polyvinylchloride (PVC) in THF for casting into thin (10-50 μm) composite films. The electrical conductivity of these films increases by more than four orders of magnitude (from 10-6 to 10-2 S/cm) when they are exposed to UV, γ-rays and e-beams. This is attributed to the dehydrochlorination (loss of HCl) of PVC by exposure to energetic particles and subsequent doping of the 2-Cl-PANI (i.e., conversion to Emeraldine Salt, ES) by the in-situ-created HCl. The doped films can also be returned to their undoped form by further exposure to NH3 vapours. The UV (or other particles)-induced doping/NH3 undoping cycles can be repeated several times until almost total dehydrochlorination of the PVC matrix. UV-Vis-NIR, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopic (XPS) techniques are employed to follow the changes in the composite films upon doping by exposure to these energetic particles.Item Open Access Lineshapes, shifts and broadenings in dynamical X-ray photoelectron spectroscopy(2009) Dâna, A.We describe in detail a model that can be used to estimate the X-ray photoelectron spectroscopic data of surfaces when a time varying bias or a modulation of the electrical properties of the surface is applied by external stimulation, in the presence of a neutralizing electron beam. Using the model and spectra recorded under periodic sample bias modulation, certain electronic properties related to charging dynamics of the surface can be estimated. The resulting technique is a non-contact impedance measurement technique with chemical specificity. Typical behavior of spectra under a square wave bias is given. Alternative modulation schemes are investigated, including small-signal square wave modulation, sinusoidal modulation and modulation of sample resistivity under fixed bias. © 2009 Elsevier B.V. All rights reserved.Item Open Access Plasmonic nano-bio sensors for detection of E-coli bacteria(IEEE, 2009) Cinel, Neval A.; Bütün, Serkan; Çalışkan, Deniz; Özbay, EkmelBiological sensors, that rely on localized surface plasmon resonance exhibited by metallic nanocylinders fabricated using electron beam lithography and functionalized with the immobilization of biotin conjugated E-coli antibodies are investigated in this study.