Characterization of thermal transport and laser absorption properties of an individual pristine SWCNT

摘要

Determination of thermal transport properties and optical absorption cross-section of nanowires is of central importance for designing nano-optoelectronics and nano-photovoltaics. Experimental study of these properties is challenging because of the very small size of a typical sample. In this study, we present a steady-state Raman method for determining the temperature (T)-dependent thermal conductivity (lambda) and laser absorption crosssection (C-abs) for an individual nanowire. This method was verified and then applied to determine lambda and C-abs of an individual pristine single-walled carbon nanotube (SWCNT, L = 22 mu m, d = 1.29 nm). The results show that lambda decreases with increasing Tin this experimental temperature range, indicating that higher temperature induces a larger scattering rate of three-phonon Umklapp processes. By measuring the temperature increase at the sample center induced by a 0.284 mW focused polarized Gaussian laser spot (514.5 nm, r(e) = 1.0 pm), we derived the absorbed laser power (P-alpha) and C-abs to be 3.98 x 10(-5) mW and 5.46 x 10(-15) m(2) for this individual SWCNT. The laser absorption cross-section per carbon atom (at) was determined to 1.64 x 10(-12) cm(2) with an uncertainty lower than 10.6%.