The influence of size effects in Pt and Au nanoparticles studied by 197Au Mossbauer spectroscopy

We present a detailed Mossbauer study of a series of Au and Pt particles in the size range from 1 to 17 nm. All measured spectra can be explained consistently with a refined model, in which the Mossbauer isomer shift varies in the inner core of a small metallic particle due to size effects. The large surface/volume ratio makes surface effects, like screening of considerable importance and even the so-called quantum-size effect may have an influence. The size evolution of the electronic properties of the particles is also discussed.