Identifying optimal metals for plasmon-based sensing: Noble vs. non-noble candidates

Abstract

The sensing capability of non-noble (Pd, Pt) and noble (Ag, Au) metals with respect to variations in size and local dielectric environment has been comprehensively investigated using the Finite-Difference Time-Domain (FDTD) method and the Drude–Lorentz model. The simulations confirm the crucial role of both the real and imaginary components of the metallic permittivity in determining the resonance condition and spectral response of nanoparticles to changes in particle dimensions and the host medium. A small variation in the real dispersion near the resonance wavelength, combined with a large norm of the permittivity, identifies Pt nanoparticles as highly reliable candidates for plasmon-based sensing devices. Among all examined metals, Pt also exhibits the lowest Quality Factor (QF), making its plasmon resonance the most sensitive to particle-size variations. In contrast, Au shows the weakest sensitivity to both particle size and the refractive index of the surrounding medium. These findings highlight the importance of incorporating non-noble metals into nanosensing platforms and provide practical guidelines for tuning nanoparticle photo-response through size, composition, and surrounding environment.