DOWNLOAD POSTER PDFStrongly heated nanoparticles have many applications ranging from cancer therapy to efficient steam generation. Gold nanoparticles may be resonantly heated when exposed to light due to the excitation of surface plasmons. Here we simulate the thermodynamics of heat transfer from a gold nanoparticle into water. This is accomplished using molecular dynamics, a large scale brute force computational technique capable of simulating the motions of millions of atoms. We study nanoparticles of experimentally realistic size, ranging from 17-26 nm containing over a hundred thousand gold atoms immersed in millions of water molecules. We show the conditions required for the formation of a vapor bubble around the nanoparticle, including the threshold laser power and the critical size of the particle. We show explicitly that small nanoparticles may be heated to the melting point without the formation of a surrounding bubble. However for larger nanoparticles, a pronounced bubble is seen around the particle. Our results are compared to the well-known heat transfer equation, which is known to break down at the nanoscale due to the formation of interfacial thermal barriers. Our work is of vital importance for scientists and engineers who wish to utilize hot nanoparticles for changing the surrounding environment, whether for irradiating a tumor cell or to produce vapor bubbles for enhanced steam generation.
