Electron Production by Sensitizing Gold Nanoparticles Irradiated by Fast Ions

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 nanopartide 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.