Browsing by Author "Avşar, D."

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Absorption and plasmon resonance of bi-metallic core-shell nanoparticles on a dielectric substrate
(Begell House Inc., 2019-06) Avşar, D.; Ertürk, H.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
Numerical investigation of absorption efficiency profiles and localized surface plasmon resonance (LSPR) wavelengths are performed for metallic core-shell nanoparticles (NPs) placed over a BK7 glass substrate. Gold (Au) and silver (Ag) metallic components are used in two different coreshell structures. This numerical study is performed with vectorized version of the discrete dipole approximation with surface interactions (DDA-SI-v). Absorption enhancement and the hybrid modes of plasmon resonances of the core-shell structures are compared by using a metric that defines a size configuration. It is observed that small volume fraction of the core sizes results in shell domination over the plasmon response. Moreover, an additional study is conducted to discern the sensitivity of the refractive index of nanoparticles in different surrounding environments. With a selected core-shell size configuration of Ag-Au pairs, a significant absorption enhancement with a redshift of LSPR wavelength is observed for both Ag core-Au shell and Au core-Ag shell NPs. These findings show the possible targeted uses of metallic core-shell nanoparticles in local heating, bio-sensing, and material detection applications.
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Effect of the probe location on the absorption by an array of gold nano-particles on a dielectric surface
(Elsevier, 2017) Moghaddam, S. T.; Avşar, D.; Ertürk, H.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
Effect of silicon atomic force microscope probe position and particle spacing on the local absorption of an array of gold nanoparticles placed over a dielectric borosilicate glass surface are evaluated. An improved, vectorized version of discrete dipole approximation coupled with surface interactions is employed throughout the study. It is shown that surface evanescent waves interacting with the system of nanoparticles and atomic force microscope probe result in a near-field coupling between them. This coupling can enhance or reduce the local absorption by the nanoparticles depending on the position of atomic force microscope tip in three-dimensional space and direction of propagation of the surface evanescent wave. The position of the atomic force microscope's tip and spacing that maximize the absorption are identified. This concept can be used for selective heating of nanoparticles placed over a surface that enables precision manufacturing at nanometer scales.
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Plasmonic responses of metallic/dielectric core-shell nanoparticles on a dielectric substrate
(IOP Publishing, 2019-06) Avşar, D.; Ertürk, H.; Mengüç, Mustafa Pınar; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
The effect of material selection on the plasmonic response and local absorption are evaluated for core- shell nanoparticles placed over a BK7 glass substrate. Eight different core-shell pairs are studied using the vectorized version of discrete dipole approximation with surface interactions (DDA-SI). Two classes of dielectric core-metallic shell and metallic core-dielectric shell particles are considered. It is shown that core-shell structures with dielectric materials can have absorption enhancement compared to the bare metallic nanoparticles. Moreover, it is observed that core-shell pairs yield multipeak localized surface plasmon resonance (LSPR) response due to their hybrid structure. Absorption enhancement and LSPR tuning ranges are shown with different dielectric materials that can be used in localized heating of designated core-shell NPs placed over a surface for nanomanufacturing purposes. In order to determine the optimum size configurations, a number of core-shell pairs are explored with specified volumetric filling ratio of core materials.