Monitoring the growth of carbon nanotubes by carbon isotope labelling

We present a C-13 labelling method for revealing the growth model of the carbon nanotubes and monitoring the detailed growth process of a multi-walled carbon nanotube (MWNT) array. C-13 ethylene and C-12 ethylene are fed into the chemical vapour deposition (CVD) reactor with pre-designed time sequences to growth MWNT arrays with C-13-C-12 sections, and the isotope compositions of each section in the nanotubes are detected by a micro-Raman after growth. By relating the positions of the isotope compositions to the corresponding feeding times, we can give obtain a detailed picture of the growth model of the carbon nanotubes as well as of the growth process of the nanotube arrays in CVD.