Size Effects on the Kinetics of Heat Transfer from a Nanoscale Diamond Particle to a Diamond Surface

Abstract

Nonequilibrium molecular dynamics simulations were performed to study the kinetics of heat transfer across the interface of a hot diamond {111} nanoparticle and a diamond {111} surface whose bulk temperature was maintained at 300 K. The heat transfer depends on the nanoparticle's interfacial energy and not its total energy. Thus, there is a linear relationship between the heat transfer rate constant, k, and the inverse of the hot nanoparticle's thickness. However, k does not depend on the nanoparticle's interfacial energy density, which decreases during its cooling, and the heat transfer occurs exponentially. For nanoparticles of fixed thickness, increasing the nanoparticle-surface interfacial contact area increases the rate for heat transfer but does not change the rate constant. The atomic-level dynamics found here, for the dependence of the heat transfer rate constant on the nanoparticle's interfacial area, thickness, and energy content, agree with Fourier's macroscopic law of heat conduction. However, for the atomic-level dynamics the dependence of the heat transfer kinetics, on the separation between the interfaces of the nanoparticle and surface, is more complex than that predicted by Fourier's law. The interfacial heat transfer dynamics found here are compared with previous studies of intramolecular vibrational energy redistribution in molecules and the prediction of Fermi's golden rule. The possible generality of the agreement found here between nanoscale heat transfer, for organic interfaces, and the prediction of Fourier's macroscopic law is discussed.

Model non-equilibrium molecular dynamics simulations of heat transfer from a hot gold surface to an alkylthiolate self-assembled monolayer

“…29 Molecular dynamics simulations have been used to study heat transfer across the interface of model diamond {111} nanosurfaces. [30][31][32] Though these simulations have provided detailed atomic-level dynamics for heat transfer at a nanoscale interface, there are no experimental studies for direct comparisons, which are important for validating the simulations. In recent experiments, 1 Dlott and co-workers studied the dynamics and kinetics of heat transfer from a hot Au {111} substrate, heated to B1073 K with a 0.5 ps laser pulse, to a physisorbed alkylthiol self-assembled monolayer (H-SAM).…”