Finite-Size Effects in Surface-Enhanced Raman Scattering from Molecules Adsorbed on Noble-Metal Nanoparticles

Vitaliy N. Pustovit; Tigran V. Shahbazyan

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Finite-Size Effects in Surface-Enhanced Raman Scattering from Molecules Adsorbed on Noble-Metal Nanoparticles

Vitaliy N. Pustovit·Tigran V. Shahbazyan

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Abstract

We study the role of strong electron confinement in surface-enhanced Raman scattering from molecules adsorbed on small noble-metal particles. We describe a new source of Raman signal enhancement which originates from different behavior of sp-band and d-band electron densities near the particle boundary. In small particles, a spillover of sp-electron wave-functions beyond the classical radius gives rise to a thin layer with diminished population of d-electrons. In this surface layer, the screening of sp-electrons by d-band electron background is reduced. We demonstrate that the interplay between finite-size and underscreening effects results in an increase of the surface plasmon local field acting on a molecule located in a close proximity to the particle boundary. Our calculations, based on two-region model, show that the additional enhancement of Raman signal gets stronger for smaller nanoparticles due to a larger volume fraction of underscreened region.

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Vitaliy N. Pustovit, Tigran V. Shahbazyan. 2004-07-13. Finite-Size Effects in Surface-Enhanced Raman Scattering from Molecules Adsorbed on Noble-Metal Nanoparticles. https://arxiv.org/abs/cond-mat/0407332

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