Beyond Extinction Efficiencies to Molar Extinction Coefficient of Silver Nanoparticles

Silver nanoparticles have garnered substantial attention across various fields owing to their distinctive optical properties, prominently including surface plasmon resonance. This study employs rigorous computational methodologies, grounded in Mie scattering theory, to analyze comprehensively the optical properties of spherical silver nanoparticles within a water medium. The analysis is specifically focused on discerning the behaviors of absorption, scattering, and extinction efficiencies for different sizes of silver nanoparticles ranging from 2.5 to 100 nm in diameters. Our investigation extends the spectral analysis to cover wavelengths up to 480 nm for larger-sized silver nanoparticles. The results reveal a distinctive dichotomy: for smaller silver nanoparticles (≤20 nm), absorption phenomena dominated the total extinction phenomena, whereas scattering phenomena emerged prominently as nanoparticle size increased. The single scattering albedo is meticulously examined, illuminating a notable transition from predominant absorption to pronounced scattering as nanoparticle sizes escalate. Furthermore, this research computes and presents detailed insights into the extinction cross sections and molar extinction coefficient for each nanoparticle size. These quantitative results provide valuable insights into the optical characteristics of silver nanoparticles, making them more versatile for use in various fields, including nanomedicine, and sensor technologies. In addition to its immediate utility, this study catalyzes a promising avenue for experimental exploration, laying the foundation for the empirical determination of molar extinction coefficient. Such experimental work promises to yield further enlightenment on silver nanoparticles, thus enriching our collective comprehension and fostering innovation in their diverse applications (Fig. 1).