Modelling the Optical Properties of Gold Nanoparticles using COMSOL Multiphysics: Influence of Geometry, Environment, and Temperature

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ABSTRACT

This study explores the optical properties of gold (Au) nanoparticles (NPs) using COMSOL Multiphysics simulation software, focusing on how these properties depend on particle geometry, surrounding environment, and temperature. A comprehensive range of nanoparticle shapes—including nanospheres, nanorods, core/shell structures, nanocubes, icosahedral shapes, and nanopeanuts—were analyzed, each with varying sizes and placed in different environments such as air, water, and silica glass. Temperature effects were studied from room temperature to 1200K, allowing for an in-depth understanding of thermal influences on optical behavior. The dielectric function of the gold nanoparticles was constructed as a function of both particle size and temperature to accurately account for their impact on optical responses. The study specifically investigated absorption, scattering, and extinction cross-sections for these nanoparticles, comparing the simulation results with existing literature. A strong agreement was observed between the modeled data and previously reported findings, validating the approach. The simulations provide key insights into the size- and temperature-dependent shifts in localized surface plasmon resonance (LSPR), crucial for applications in fields such as biomedicine, thermal therapy, and imaging. These findings are particularly useful in designing gold nanoparticles with tailored optical properties for targeted applications, including drug delivery and diagnostic imaging. This work represents a holistic approach to modeling the optical properties of gold nanoparticles, addressing both geometrical and environmental influences as well as thermal effects, providing a valuable tool for future nanoparticle-based technologies.

Significance of the study:

This study offers critical insights into the optical properties of gold nanoparticles (Au NPs), providing a robust framework for tuning their behavior based on size, shape, environment, and temperature. Such control is essential for optimizing Au NPs for applications in fields like biomedicine, photothermal therapy, and imaging. By validating the simulation results with existing literature, the study enhances the reliability of computational models, paving the way for the design of highly specific nanoparticle-based technologies.

Summary of the study:

The study investigates the optical properties of gold nanoparticles (Au NPs) using COMSOL Multiphysics simulations, exploring the effects of geometry, environment, and temperature. Various shapes, including nanospheres, nanorods, and core/shell structures, were analyzed in different media, and the dielectric function was modeled as a function of size and temperature. Results showed that larger particle sizes and higher temperatures cause a red-shift in localized surface plasmon resonance (LSPR), offering insights for tailoring Au NP properties for applications like imaging and drug delivery.