Thermal transport across the interface between a suspended single-walled carbon Nanotube and air

The heat transfer coefficients of several individual single-walled carbon nanotubes (SWCNTs) were measured using a micro-Raman spectroscopy technique in an atmosphere environment. A 514 nm laser was focused in the middle of a suspended SWCNT and the local temperature rise was measured by monitoring the downshifts of the G-band frequency. The heat transfer coefficient can be extracted from the measured midpoint temperature rise. Because there are no temperature drops at the ends of SWCNTs, the thermal contact resistance can be ignored. A detailed kinetic model was developed to predict the heat transfer coefficient quantitatively from the free molecular regime to the continuum regime. The theoretical prediction agrees well with the experimental data. Based on the present model, a maximum heat transfer coefficient occurs in the transition regime at a diameter of several nanometers, which is the competition result of the thermal resistances of the noncontinuum layer and continuum layer. The maximum value agrees with the prediction of kinetic theory of gases. The noncontact Raman measurement technique and prediction model will benefit the thermal design of carbon nanotube-based heat spreaders.