Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651

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Citation - WoS: 107
Citation - Scopus: 111
Determination of Complete Melting and Surface Premelting Points of Silver Nanoparticles by Molecular Dynamics Simulation
(Amer Chemical Soc, 2013) Yavuz, M.; Zhou, Y.; Alarifi, H. A.; Atis, M.; Ozdogan, C.; Hu, A.
A molecular dynamics simulation based on the embedded-atom method was conducted at different sizes of single-crystal Ag nanoparticles (NPs) with diameters of 4 to 20 nm to find complete melting and surface premelting points. Unlike the previous theoretical models, our model can predict both complete melting and surface premelting points for a wider size range of NPs. Programmed heating at an equal rate was applied to all sizes of NPs. Melting kinetics showed three different trends that are, respectively, associated with NPs in the size ranges of 4 to 7 rim, 8 to 10 nm, and 12 to 20 nm. NPs in the first range melted at a single temperature without passing through a surface premelting stage. Melting of the second range started by forming a quasi-liquid layer that expanded to the core, followed by the formation of a liquid layer of 1.8 nm thickness that also subsequently expanded to the core with increasing temperature and completed the melting process. For particles in the third range, the 1.8 nm liquid layer was formed once the thickness of the quasi-liquid layer reached S rim. The liquid layer expanded to the core and formed thicker stable liquid layers as the temperature increased toward the complete melting point. The ratio of the quasi-liquid layer thickness to the NP radius showed a linear relationship with temperature.
Citation - WoS: 27
Citation - Scopus: 31
The Effects of Lattice Motion on Eley-Rideal and Hot Atom Reactions: Quasiclassical Studies of Hydrogen Recombination on Ni(100)
(Amer Chemical Soc, 2002) Guvenc, ZB; Sha, XW; Jackson, B
Quasiclassical methods are used to simulate the interactions of H or D atom beams with D- or H-covered Ni(100) surfaces. The Ni substrate is treated as a multilayer slab, and the Ni atoms are allowed to move. The model potential energy surface is fit to the results of detailed total-energy calculations based on density functional theory. Most of the incident atoms trap to form hot atoms, which can eventually react with an adsorbate, or dissipate their energy and stick. The incident atom is found to lose several tenths of an eV of energy into the metal, upon initially colliding with the surface. This limits reflection to a few percent, at all coverages, and secondary reactions between adsorbates are significantly lowered. Long time hot atom reactions are also found to be damped out by the inclusion of lattice motion, leading to increased sticking, even at high coverages where dissipation into the adsorbates should be the primary energy loss mechanism. Overall, the inclusion of lattice motion is found to improve agreement with experiment.
Vertical Self-Assembly of Gold Nanoworms for Sensitive Surface-Enhanced Raman Spectroscopy-Based Trace Detection
(Amer Chemical Soc, 2025) Khan, Ghazanfar Ali; Demir, Ahmet Kemal; Demirtas, Ozge; Tasgin, Dilek Isik; Bek, Alpan; Bhatti, Arshad Saleem; Ahmed, Waqqar
The assembly of anisotropic nanoparticles into closely packed structures results in unique functionalities. Herein, we report a 3D multilayer vertical assembly of worm-shaped Au nanoparticles using a carefully regulated evaporation-induced deposition method. With the evaporation of the nanoworm (NW) suspension, the concentration of NWs in the suspension gradually increases, which generates a balance between electrostatic interactions and entropically driven attraction to produce multilayer vertical assemblies. These assemblies exhibit enhanced surface-enhanced Raman scattering (SERS) signals due to the presence of a high concentration of hotspots. Moreover, in contrast to nanorods, the bent morphology of NWs creates pores in the vertical assembly, enabling the analyte molecule to penetrate the assembly and access hotspots. Picomolar to micromolar concentrations of rhodamine 6G (R6G) were detected with the NW assembly-based SERS substrate with excellent linearity and uniformity of the signal with a spot-to-spot relative standard deviation (RSD) of only 8.9%. The SERS substrates were also employed for trace detection of ammonium nitrate, which is a well-known constituent of homemade explosives. Our method of producing multilayer vertical assemblies of NWs is simple, highly sensitive, stable, and reproducible for making effective SERS sensors for the quantitative detection of analytes.

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