Ellipsometric Study on Size-Dependent Melting Point of Nanometer-Sized Indium Particles

Size-dependent melting properties of nanometer-sized Indium particles with size ranging from 25.5 to 68.1 nm were studied by spectroscopic ellipsometry, and a critical size is found between 42.4 and 44.9 nm. The melting points of nanometer-sized Indium particles with size larger than critical size are almost the same as that of bulk indium, while no clear melting point was found for indium particles with size smaller than the critical size. A knee point defined as the average melting point was introduced to characterize the melting of these smaller size particles, and it depresses with decreasing size. The mechanism for size dependent melting of indium particles was discussed. This work shows that spectroscopic ellipsometry is an effective optical tool for characterizing the melting of nanometer-sized metal particles.