Electron surface scattering and quantum finite-size effect on dielectric and optical properties of thin gold films

Abstract

With the size of metal nanostructures entering into the nanoscale region, electron surface scattering and quantum finite-size effect gradually dominate the physical properties of surface plasmon resonances. In this context, we investigate both the quantum corrected dielectric functions and the absorption spectra of thin gold films for different thickness by excluding and including electron surface scattering. Our results show that when don't taking into account electron surface scattering, the multiple peaks appear for both the quantum-corrected dielectric functions and the absorption spectra of thin gold films, which features the discretization of electronic states in small quantum-sized system. When including electron surface scattering, however, the multipeak structures are masked and even disappear due to a large broadening of themselves. The transition from the quantum results to the classical ones for increasing thickness is also clearly demonstrated for the two cases. Although we only discuss the dielectric function and optical absorption of gold films with quantum sizes, the phenomena are expected to be exhibited in other metal nanostructures. Our findings enrich our understanding of both electron surface scattering and quantum finite-size effect in small metal nanostructures, and pave the way for the designs of quantum plasmonic devices.