Physical and Optical Properties of Silver Nanoparticles 

At the nanoscale, silver’s properties differ significantly from its bulk form, these differences are primarily driven by particle size, shape, and interaction with light. The physical characteristics of silver nanoparticles such as size, shape, and surface chemistry play a crucial role in defining their performance in research and applied systems.

Size & Distribution

Particle size is one of the most critical factors influencing the optical performance of plasmonic silver nanoparticles. It directly impacts the resonance wavelength, scattering and absorption efficiency, and sensitivity to changes in the local refractive index all of which are essential for technologies like LSPR and SERS.

Silver nanoparticles within the 30 to 120 nm range offer a balance between strong plasmonic activity and colloidal stability. In practical terms, this size range supports sharp, tunable plasmonic peaks and enables high surface-to-volume ratios, which are essential for maximizing analyte interactions and signal intensity.

A narrow size distribution is essential because it ensures that the particles have nearly identical dimensions, leading to:

• Consistent and sharp plasmonic peaks, without spectral broadening
• Reproducible optical and sensing performance across experiments
• Higher signal-to-noise ratios in applications such as LSPR and SERS

Without uniform sizing, the optical response becomes smeared and unpredictable, ultimately reducing both sensitivity and accuracy in analytical and diagnostic applications.

At SciVentions, we synthesize monodisperse silver nanoparticles with tight size distributions to ensure consistent optical behavior. We routinely characterize our samples using Dynamic Light Scattering (DLS) to confirm particle size and distribution, ensuring quality and reliability with every batch.

Shape 

The shape of silver nanoparticles plays a pivotal role in determining their plasmonic behavior. Different geometries such as spheres, rods, prisms, cubes, and decahedra support distinct plasmon modes, which directly influence the resonance wavelength, field localization, and optical intensity.

For example, triangular prisms and decahedra exhibit sharp tips and edges that concentrate electromagnetic fields, creating strong “hot spots” essential for SERS. Shape also controls the tunability of the LSPR peak. Spherical particles typically produce a single, symmetric plasmon band in the 400–450 nm range, while anisotropic shapes like rods and prisms enable multiple resonance modes—allowing plasmonic peaks to be tuned well into the near-infrared region.

This tunability makes shape-controlled nanoparticles highly valuable for applications requiring specific spectral positioning, such as biosensing, photothermal therapy, and multiplexed detection.

SciVentions uses a light-mediated shape selection process in which high-intensity LEDs are shined onto the nanoparticle reaction mixture during synthesis. This controlled illumination selectively promotes the growth of specific nanoparticle facets while suppressing others, resulting in highly uniform, anisotropic shapes such as decahedra, prisms, and nanorods. By tuning the wavelength and intensity of the light source, we can precisely guide the morphology of the silver nanoparticles, enabling sharp plasmonic peaks and optimized optical performance tailored to advanced sensing applications.