Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Topçu, GökhanPublisher: search.filters.publisher.Elsevier

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 3
    Citation - Scopus: 6
    Hybrid Photonic-Plasmonic Mode-Coupling Induced Enhancement of the Spontaneous Emission Rate of Cds/Cdse Quantum Emitters
    (Elsevier, 2022) Gökbulut, Belkıs; İnanç, Arda; Topçu, Gökhan; Özçelik, Serdar; Demir, Mustafa Muammer
    n this paper, a hybrid photonic-plasmonic resonator, which comprises an electrospun polymer fiber with a micrometer diameter and a core/shell nanostructure with a gold nanoparticle core, is constructed to investigate the dynamics of the coupled spontaneous emission of CdS/CdSe quantum dots (QDs). The gold nanoparticle core; covered with a silica shell, anchored with individual CdS/CdSe QDs, is placed inside a hollow cylindrical nanocavity formed on the surface of the microfiber to enable integration of the optical mode with the plasmonic effect, which is induced by the localized surface plasmons of the metal nanoparticle being present in the vicinity of the dipoles. The spontaneous emission rate of the QDs, coupled into the hybrid photonic-plasmonic mode, is measured to enhance by a factor of 23 via a time-resolved experimental technique. This result suggests that the regeneration of the optical mode-field inside the photonic-plasmonic resonator through the interaction of the dipoles with the localized surface plasmons of a metal nanoparticle strongly enhances the density of the electromagnetic states of the quantum emitters to facilitate an enhanced spontaneous emission within the host medium of the proposed polymer based-photonic structure.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 5
    Plasmon-Induced Spectral Tunability of Perovskite Nanowires
    (Elsevier, 2021) Gökbulut, Belkıs; Topçu, Gökhan; Demir, Mustafa Muammer; İnci, Mehmet Naci
    In this paper, plasmon-assisted spectral tunability in random media, composed of Perovskite (CsPbBr3) nanowires surrounded by Au nanoparticle clusters in polystyrene matrix, is achieved. The interaction between the surface plasmons and the quantum sources is observed to generate photoluminescence from the higher excited state energy levels of the excited semiconductor nanowires, which results in a blueshifted fluorescence emission of 50 nm. The localized surface plasmon properties are also determined to be tuned by plasmonic pumping of the quantum sources at different resonant frequencies. Thus, the first observation of the tunable blueshifted fluorescence emission of the semiconductor nanocrystals surrounded by plasmonic nanoparticle aggregates is achieved. The dramatic changes in the spectral profiles of the fluorescent nanowires are attributed to be due to the fast dynamics surface enhanced fluorescence mechanism.
  • Article
    Citation - WoS: 25
    Citation - Scopus: 28
    Colorimetric and Plasmonic Pressure Sensors Based on Polyacrylamide/Au Nanoparticles
    (Elsevier, 2019) Topçu, Gökhan; Güner, Tuğrul; İnci, Ezgi; Demir, Mustafa Muammer
    Colorimetric stimuli-responsive nanomaterials have emerged as an eminent tool for sensor applications. Among this class of sensing elements, gold nanoparticle-based (Au NP) nanostructures are promising materials due to their plasmonic features. In this study, free-standing flexible polymeric films having intense optical response upon application of mechanical pressure were fabricated based on polyacrylamide (PAAm) and Au NPs. Pressure may cause plasmonic shift most probably due to the disassembly of the clusters from blue to reddish individual particles depending on the extent of pressure. Temperature, time, and extent of pressure were examined in terms of spectral change of Au particles. The sensor films depict working range up to 160 MPa, which shows minor change at elevated temperatures probably due to the stress induced crystallization of PAAm. For practical applications, a simple red-green-blue (RGB) space-based algorithm was presented for smartphone-assisted detection of applied pressure. Moreover, the PAAm/Au composite structure shows self-healing without any additive under ambient conditions even after divided into pieces. (C) 2019 Elsevier B.V. All rights reserved.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 24
    Colloidal Films of Sio2 in Elastomeric Polyacrylates by Photopolymerization: a Strain Sensor Application
    (Elsevier, 2020) İnci, Ezgi; Topçu, Gökhan; Demir, Mustafa Muammer
    Thin layer SiO2 colloidal films show angle-dependent coloration (iridescence) based on constructive interference, rather than absorption, without the existence of pigments. The transfer of thin layered colloidal film into a transparent elastomeric matrix maintaining its color may allow the fabrication of colorimetric strain sensors. In this study, trilayer SiO2 colloidal films were prepared by Langmuir-Blodgett deposition using a binary solvent system (chloroform/methanol) and this structure is successfully transferred into poly(ethylene glycol) phenyl ether acrylate elastomer via lateral capillary force. The resulting composite films exhibit iridescence depending on the particle size, therefore, film thickness as similar in mere colloidal films with a slight difference due to change in efficient refractive index (neff). Uniaxial extension of the composite film up to 50 % strain causes a remarkable linear shift in reflection signal from 568 to 496 nm. The change in thickness of the composite film accordingly intercolloidal distance normal to the application of mechanical stretching causes variation of the reflection of light.