Energy Accommodation between Noble Gases and Carbon Nanotubes

Abstract

Molecular dynamics simulations are used to predict the energy accommodation coefficients (EACs) between the noble gases He, Ne, and Ar and the outside of single-walled carbon nanotubes (CNTs) with diameters between 0.41 and 6.10 nm at a temperature of 300 K. The EAC increases monotonically with CNT diameter and approaches the value predicted for graphene. The EAC also increases monotonically with gas atom mass. The CNT EAC data collapse to a linear trend when they are normalized by the graphene EAC and plotted versus the depth of their potential energy well on the CNT normalized by that for graphene. The EACs are used to estimate that the thermal boundary conductance between noble gases and graphene will be of order 0.1 MW/m2·K at a gas pressure of 1 atm, corresponding to a gas Kapitza length of order 100 nm.