Electron production by sensitizing gold nanoparticles irradiated by fast ions

TL;DR

This paper investigates how gold nanoparticles, when irradiated by fast ions, significantly increase electron emission through collective excitations like plasmons and atomic resonances, which has implications for radiation biology.

Contribution

It introduces a model to estimate electron yield from gold nanoparticles under ion irradiation, highlighting the role of collective excitations and validating the approach with density-functional theory calculations.

Findings

Gold nanoparticles enhance electron emission compared to water.

Collective excitations like plasmons significantly contribute to electron yield.

Decay of excitations in biological media is a key electron production mechanism.

Abstract

The yield of electrons generated by gold nanoparticles due to irradiation by fast charged projectiles is estimated. The results of calculations are compared to those obtained for pure water medium. It is demonstrated that a significant increase in the number of emitted electrons arises from collective electron excitations in the nanoparticle. The dominating enhancement mechanisms are related to the formation of (i) plasmons excited in a whole nanoparticle, and (ii) atomic giant resonances due to excitation of d electrons in individual atoms. Decay of the collective electron excitations in a nanoparticle embedded in a biological medium thus represents an important mechanism of the low-energy electron production. Parameters of the utilized model approach are justified through the calculation of the photoabsorption spectra of several gold nanoparticles, performed by means of time-dependent density-functional theory.