Xiaomin Tu, Angela R. Hight Walker, Ming Zheng


We have previously demonstrated that DNA is capable of recognizing (n, m) carbon nanotube structure through the purification of 12 semiconducting carbon nanotubes from a synthetic mixture with the assistance of ion-exchange chromatography.  Here we report that metallic armchair tubes can be purified as well by the DNA approach.  We determined the structures of the purified species are the highly symmetric armchair-type, such as (6, 6), (7, 7), (8, 8) etc, by optical absorption and Raman spectroscopy.  Armchair nanotubes have unique structures, from which many interesting properties result, e.g. they are believed to behave as quantum wires that can revolutionize the electric grid system.  Hence, availability of homogenous population of chirally pure material may be of great significance to fundamental studies and advanced applications.