Abstract
Anisotropic gold nanoparticles, such as gold nanorods, are of significant interest due to their tunable aspect ratios, which directly influence their optical properties and plasmonic behavior. Control over these parameters enables enhancement of plasmon resonance for applications in catalysis, photothermal therapeutics, and nano photonics. Self-assembled nanorod dimers further enhanced electric field for aforementioned applications. However, a major challenge in nanoparticle assembly is achieving a high yield of dimers while suppressing the formation of larger, uncontrolled aggregates. This research focuses on optimizing reaction conditions to promote selective dimer formation of gold nanorods through wet chemical methods with particular emphasis on pH control and reaction kinetics. By fine-tuning these parameters, the work aims to regulate interparticle coupling and minimize aggregation beyond the dimer state. Dimerized nanoparticles enable strong plasmonic coupling and localized electromagnetic field enhancement, which are critical for high sensitivity of plasmonic sensing applications. Structural and optical characterization of nanorod dimers are conducted using scanning electron microscopy, UV-Vis spectroscopy while dynamic light scattering is discussed as a complementary technique for evaluating size distribution and surface charge in solution. Overall, this work provides insight into the controlled formation of gold nanorod dimers and establishes strategies to enhance yield.