Yazar "Gultekin, Aytac" seçeneğine göre listele

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    The influence of CdS quantum dots incorporation on the properties of CdO thin films
    (EDP SCIENCES S A, 2013) Gultekin, Aytac; Karanfil, Gamze; Ozel, Faruk; Kus, Mahmut; Say, Ridvan; Sonmezoglu, Savas
    The aim of our work is to obtain nano-structured cadmium oxide (CdO) thin films by sol-gel spin coating method and to investigate the effects of cadmium sulfide quantum dots (CdS QDs) doping on the structural modification and surface morphology evolution. X-ray diffraction (XRD) results show that the intensities of the peaks of the crystalline phase increase with the increase in CdS QDs concentrations. From scanning electron microscopy (SEM) images, the distinct variations in the morphology of the thin films were also observed. In addition, the evolution of surface morphology, roughness and granularity has been characterized by atomic force microscopy (AFM). Moreover, we have performed the optical characteristics of the thin films such as transparency, energy band gap and Urbach tail. The optical band gap of the thin films increases from 2.23 to 2.51 eV with the increase in CdS QDs concentrations due to the Moss-Burstein effect. The enhanced values of the transparency, energy band gap and crystallity indicate that addition of CdS QDs can be used to modify the optical, structural and morphological properties of CdO thin films.
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    Preparation of MIP-based QCM nanosensor for detection of caffeic acid
    (ELSEVIER SCIENCE BV, 2014) Gultekin, Aytac; Karanfil, Gamze; Kus, Mahmut; Sonmezoglu, Savas; Say, Ridvan
    In the present work, a new caffeic acid imprinted quartz crystal microbalance (QCM) nanosensor has been designed for selective assignation of caffeic acid in plant materials. Methacrylamidoantipyrine-iron (III) [MAAP-Fe(III)] as metal-chelating monomer has been used to prepare selective molecular imprinted polymer (MIP). MIP film for detection of caffeic acid has been developed on QCM electrode and selectivity experiments and analytical performance of caffeic acid imprinted QCM nanosensor has been studied. The caffeic acid imprinted QCM nanosensor has been characterized by AFM. After the characterization studies, imprinted and non-imprinted nanosensors was connected to QCM system for studies of connection of the target molecule, selectivity and the detection of amount of target molecule in real samples. The detection limit was found to be 7.8 nM. The value of Langmuir constant (b) (4.06 x 10(6)) that was acquired using Langmuir graph demonstrated that the affinity of binding sites was strong. Also, selectivity of prepared caffeic acid imprinted nanosensor was found as being high compared to chlorogenic acid. Finally, the caffeic acid levels in plant materials was determined by the prepared QCM nanosensor. (C) 2013 Elsevier B.V. All rights reserved.
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    Synthesis and characterisations of Au-nanoparticle-doped TiO2 and CdO thin films
    (PERGAMON-ELSEVIER SCIENCE LTD, 2014) Gultekin, Aytac; Karanfil, Gamze; Ozel, Faruk; Kus, Mahmut; Say, Ridvan; Sonmezoglu, Savas
    In the present study, pure and gold nanoparticle (Au NP)-doped titanium dioxide (TiO2) and cadmium oxide (CdO) thin film were prepared by the sal-gel method, and the effect of Au NP doping on the optical, structural and morphological properties of these thin films was investigated. The prepared thin films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible-near infrared (UV-Vis-NIR) spectra. While the optical band increases from 3.62 to 3.73 for TiO2 thin films, it decreases from 2.20 to 1.55 for CdO thin films with increasing Au doping concentration. Analysis of XRD indicates that the intensities of peaks of the crystalline phase have increased with the increasing Au NP concentrations in all thin films. SEM images demonstrate that the surface morphologies of the samples were affected by the incorporation of Au NPs. Consequently, the most significant results of the present study are that the Au NPs can be used to modify the optical, structural and morphological properties of TiO2 and CdO thin films. (C) 2014 Elsevier Ltd. All rights reserved.