Evaluation of local temperature around the impact points of fast ions

Gold and platinum nanoparticles of few-nm size were deposited on amorphous silicon nitride (a-SiN) films. These samples were irradiated with 1.1 MeV C603+ ions to a fluence of ∼5 × 1010 ions/cm2 and observed using transmission electron microscopy (TEM). The ion tracks were clearly seen as bright spots and the metal nanoparticles disappeared from a neighboring region (5–10 nm) around each ion track. The platinum-nanoparticle-cleared region is slightly smaller than that of gold nanoparticles. This trend can be reproduced by the u-TS calculations assuming that the nanoparticles are desorbed when the local temperature surpasses the melting point of nanoparticles as was predicted by molecular dynamics simulations (Anders et al., 2009). This indicates that the temperature distribution in a nanometer region can be evaluated by observing the desorption of nanoparticles of different metals having different melting temperatures.