Effects of Damping Constant of Electron and Size on Quantum-Based Frequency-dependent Dielectric Function of Small Metallic Plasmonic Devices

Electron surface dissipation and quantum-limited size tend to control the material properties of exterior plasmon oscillation as the size of metal nanoparticles goes into the nanoscale domain. The need to examine this characteristic behaviour and its potential becomes imperative. This study explores the effects of the damping constant of electrons and size quantum-based frequency-dependent dielectric function (FDDF) of small metallic materials using an elementary model of electrons in a confined box. The frequency-dependent dielectric function is employed to study quantum size impacts and damping constant in the optical spectra region. The quantum amended frequency-dependent dielectric function and the absorbing spectra of silver-cube geometry for different sizes by adding damping constant and without damping constant are critically examined. The findings reveal that when the damping constant effect is absent, the multiple crests emerge for the quantum-amended frequency-dependent dielectric function and absorbing spectra of the metallic materials, highlighting the electronic discretization levels in the tiny quantum-limited structure. While the damping constant is included, the multiple summits are hidden and vanish owing to a considerable widening of the structures independently. The change in the numerical results from the quantum case to the classical case for growing widths is further illustrated for both cases. The numerical results enhance our knowledge of damping constant dissipation and quantum limited-size impact in small-scaled plasmonic devices.