Influence of metallic nanoparticles on upconversion processes

TL;DR

This paper derives equations to analyze how metallic nanoparticles influence upconversion processes, comparing them to Raman and fluorescence, and explores optimal nanoparticle sizes for enhancing upconversion signals, with implications for solar energy applications.

Contribution

It introduces simple analytical equations for metallic nanoparticle effects on upconversion, highlighting differences from Raman and fluorescence, and provides numerical simulations for optimal particle sizes.

Findings

Nanoparticles of 100-400nm radius enhance upconversion signals.

Significant differences exist between nanoparticle effects on upconversion versus Raman and fluorescence.

Challenges remain in applying metallic particles for solar energy upconversion.

Abstract

It is well known that Raman scattering and fluorescence can be enhanced by the presence of metallic nanoparticles. Here, we derive simple equations to analyse the influence of metallic nanoparticles on upconversion processes such as non-radiative energy transfer or excited state absorption. We compare the resulting expressions with the more familiar Raman and fluorescence cases, and find significant differences. We use numerical simulations to calculate the upconverted signal enhancement achievable by means of metallic spheres of different radii, and find particles of 100-400nm radius at infrared frequencies to be favorable. We also discuss the considerable challenges involved in using metallic particles to enhance upconversion for solar energy.