Broadening of resonances in yttrium nanoparticle optical spectra

The dielectric function of yttrium in the range between 0.2 mum and 2 mum i s composed of a harmonic oscillator contribution due to a discrete interban d transition and the contribution of free electrons. Hence, it is possible to discuss surface plasmon polaritons as well as other electronic resonance s in the optical extinction spectra of yttrium nanoparticles. For the latte r, we discuss the broadening of the resonance caused by the aggregation of particles. When particles are lumped into aggregates, the color of the part icle system also changes. Aggregation also affects the surface plasmon reso nance in yttrium nanoparticles in a way comparable to silver or gold nanopa rticle aggregates. Comparison is made with the first experimental results o n yttrium nanoparticles, showing that aggregation is the dominant effect fo r the broad resonance in the measured extinction spectra.