Optical visualization and polarized light absorption of the single-wall carbon nanotube to verify intrinsic thermal applications

Abstract

The predicted extraordinary properties of carbon nanotubes (CNTs) from theoretical calculations have great potential for many applications. However, reliable experimental determination of intrinsic properties at the single-tube level is currently a matter of concern, and many challenges remain because of the unhandled and nanoscale size of individual nanotubes. Here, we demonstrated a prototype to detect the intrinsic thermal conductivity of the single-wall carbon nanotube (SWCNT) and verify the significant non-resonant optical absorption behavior on tiny nanotubes by integrating the nanotube and ice into a new core-shell design. In particular, a reversible optical visualization method based on the individual suspended ultra-long SWCNT was first developed by wrapping a nanotube with ice in the cryogenic air environment. The light-induced thermal effect on the hybrid core-shell structure was used to melt the ice shell, which subsequently acted as a temperature sensor to verify the intrinsic thermal conductivity of the core-like nanotube. More interestingly, we successfully determined for the first time the thermal response phenomenon of the tiny absorption cross section in SWCNT in the vertical-polarization configuration and the significant non-resonant absorption behavior in the parallel-polarization configuration. These investigations will provide a better understanding for the unique optical behaviors of CNT and enable the detection of intrinsic properties of various one-dimensional nanostructures such as nanotubes, nanowires, and nanoribbons. Growing ice on a carbon nanotube not only enables the nanotube to be optically imaged but also permits its thermal properties to be measured. Isolated single-walled carbon nanotubes with diameters of just a few nanometres are usually impossible to observe using an optical microscope. Now, Xiao Zhang and other scientists in China have discovered a non-destructive and reversible way to optically observe carbon nanotubes and measure their thermal properties. Their method involves growing a few-micrometre-thick layer of ice on a suspended nanotube by placing it in a cryogenic environment. The researchers then melted the ice by irradiating the ice-coated nanotube with a laser beam, while inferring the nanotube s temperature from a shift in its Raman signal. From this information, they could determine the intrinsic thermal conductivity and the light absorption behavior of the nanotube.