Effect of microwave irradiation on carbon nanotube fibers: exfoliation, structural change and strong light emission

Abstract

We exposed single- and double-walled carbon nanotube (SWCNT and DWCNT) fibers to microwave radiation. Small carbon clusters of C₂ were detached from the nanotubes, and the process was accompanied by intense heat release. The exfoliation of C₂ made the nanotubes break, while the high temperature made the nanotube bundles transform into large diameter CNTs. Strong visible light emission was observed from the vicinity of the nanotube fibers. The emission spectra excited by the microwaves from the as-grown CNT fibers correspond to the Swan band of C₂ clusters. In the case of the purified SWCNT fibers, two characteristic peaks at 584 nm and 769 nm emerge in the spectra beyond the Swan band of C₂.