Responses of Multiwalled Carbon Nanotubes of Different Diameters to Microwave Irradiation

We studied the ultraviolet, visible, and infrared radiation emitted by multiwalled carbon nanotubes of different diameters when exposed to 2.45 GHz microwaves. A comparison of the spectra suggests that multiwalled carbon nanotubes with larger diameters emit radiation of greater intensity than those with smaller diameters. Furthermore, the multiwalled carbon nanotubes continued to emit radiation over the course of several microwave-irradiation cycles, with no degradation in the intensity of the emitted radiation. A comparison of Raman D- to G-band peak-intensity ratios revealed that microwave-irradiation did not significantly impact the multiwalled carbon nanotubes’ defect densities. The results of our experiments suggest that multiwalled carbon nanotubes may have the potential for use in lighting technologies, and that ohmic heating caused by the polarization of the multiwalled carbon nanotubes in the microwave field is likely responsible for the observed emissions of visible and infrared radiation.