Browsing by Author "Huda, G. M."

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    Absorption suppression of silver nanoparticles in the presence of an AFM tip: A harmonic oscillator model
    (AIP, 2012) Huda, G. M.; Mengüç, Mustafa Pınar; Hastings, J. T.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
    We numerically calculated the optical absorption of silver nanoparticles (AgNP) in the presence of metallic and dielectric AFM probes, illuminated by transverse magnetic (TM) polarized, total internal reflected waves. Nanoscale probes localize and enhance the field between the apex of the tip and the particle. However, such probes can actually suppress the optical absorption of the AgNP. To better understand this phenomenon, we fitted the numerical absorption data with the equation of a driven damped harmonic oscillator (HO), and we found that the AFM tip modifies both the driving force and increases the overall damping of the oscillator by introducing an additional radiative decay path. For a 50 nm diameter AgNP the introduction of either a metallic or dielectric AFM probe suppresses absorption.
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    Comparison between discrete dipole approximation and other modelling methods for the plasmonic response of gold nanospheres
    (Springer Science+Business Media, 2014-05) Loke, Vincent L. Y.; Huda, G. M.; Donev, E. U.; Schmidt, V.; Hastings, J. T.; Mengüç, Mustafa Pınar; Wriedt, T.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
    We investigate the plasmonic response of gold nanospheres calculated using discrete dipole approximation validated against the results from other discretization methods, namely the finite-difference time-domain method and the finite-element methods. Comparisons are also made with calculations from analytical methods such as the Mie solution and the null-field method with discrete sources. We consider the nanoparticle interacting with the incident field both in free space and sitting on a planar substrate. In the latter case, discrete dipole approximation with surface interaction is used; this includes the interaction with the 'image dipoles' using Sommerfeld integration.
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    Conference ObjectPublicationOpen Access
    Discrete dipole approximation of gold nanospheres on substrates: considerations and comparison with other discretization methods
    (AAPP Physical, Mathematical, and Natural Sciences, 2011) Loke, Vincent L. Y.; Donev, E. U.; Huda, G. M.; Hastings, J. T.; Mengüç, Mustafa Pınar; Wriedt, T.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
    We embark on this preliminary study of the suitability of the discrete dipole approximation with surface interaction (DDA-SI) method to model electric field scattering from noble metal nano-structures on dielectric substrates. The refractive index of noble metals, particularly due to their high imaginary components, require smaller lattice spacings and are especially sensitve to the shape integrity and volume of the model. The results of DDA-SI model are validated against those of the well-established finite element method (FEM) and the finite difference time domain (FDTD) method.