Fouquet, M.; Bayer, B.C.; Esconjauregui, S.; Blume, R.; Warner, J.H.; Hofmann, S.; Schlögl, R.; Thomsen, C.; Robertson, J.: Highly chiral-selective growth of single-walled carbon nanotubes with a simple monometallic Co catalyst. Physical Review B 85 (2012), p. 235411/1-7
10.1103/PhysRevB.85.235411

Abstract:
We report on the growth of single-walled carbon nanotubes from a monometallic Co catalyst on an oxidized Si wafer support by the most simple growth recipe (vacuum annealing, growth by undiluted C2H2). Nevertheless, multiwavelength Raman spectroscopy and transmission electron spectroscopy show a remarkable selectivity for chiral indices and thus, e.g., high abundance with a single chirality representing 58% of all semiconducting tubes. In situ x-ray photoelectron spectroscopy monitors the catalyst chemistry during carbon nanotube growth and shows interfacial Co-Si interactions that may help to stabilize the nanoparticle/nanotube diameter. We outline a two-mechanism model explaining the selective growth.