Growth of carbon nanotube arrays using the existing array as a substrate and their Raman characterization

In this Letter, we report that after oxidation in air and reduction in hydr ogen the existing carbon nanotube arrays can be used as a substrate to grow another nanotube array. The two arrays are connected through a thin cataly st layer. Micro-Raman study of these two nanotube arrays shows that they ha ve different characteristic spectra. Besides the small shift in the peak fr equencies of the two kinds of arrays in Micro-Raman spectra, we have observ ed changes in the relative intensities of D, G and D' lines and proposed th e mechanism of this phenomenon. (C) 2001 Elsevier Science B.V, All rights r eserved.