Reduced diameter distribution of single-wall carbon nanotubes by selective oxidation E. Borowiak-Palen a,b, * , T. Pichler a,c ,X.Liu a , M. Knupfer a , A. Graff a , O. Jost d , W. Pompe d , R.J. Kalenczuk b , J. Fink a a Institute for Solid State and Materials Research Dresden, P.O. Box 270016, Dresden D-01171, Germany b Institute of Chemical and Environment Engineering, Technical University of Szczecin, Poland c Institut f€ ur Materialphysik, Universit€ at Wien, Strudlhofg. 4, Wien A-1090, Austria d Institute for Materials Science, Dresden University of Technology, Dresden D-01062, Germany Received 4 June 2002; in final form 29 July 2002 Abstract We report an easy way to narrow the diameter distribution of single-walled carbon nanotubes (SWNT) by oxidi- zationtreatments.Bothachemicaltreatmentin2MHNO 3 aswellasoxidationinareducedO 2 atmosphere lead to a selectiveburningofthenarrowerSWNTinbulksamplesandtoadiameterdistributionwhichissmallerbyafactorof two. This is a first important step towards a selective production of SWNT with a defined diameter on a bulk scale. Ó 2002 Elsevier Science B.V. All rights reserved. 1. Introduction Carbon nanotubes have aroused great excite- ment among physicists, chemists and material scientists due to their unique physical properties whichspananextremelywiderange[1].Especially, single-wall carbon nanotubes (SWNT) are cur- rently being intensively investigated worldwide since they possess unique and intriguing electronic properties.SWNTcanbeeithersemiconductingor metallic depending on the geometrical structure defined by the chirality [2]. Several methods [3–6] for large scale synthesis of carbon nanotubes have opened the door to study their physical and chemical properties on a bulk scale. However, the as-produced SWNT are found with a distribution of various diameters and chiralities. Furthermore, the as-prepared carbon nanotubes usually contain a large amount of impurities, such as metal parti- cles, amorphous carbon and multishell carbon nanocapsules. These facts render a serious im- pediment to a detailed characterization of the propertiesofthenanotubesandtheirapplications. Thus, a purification of the SWNT with high se- lectivity after production becomes important. Many attempts to purify the as-prepared SWNT material [7–15] have been performed but, to our knowledge,noquantificationofthechangesofthe diameter distribution is available. 16 September 2002 Chemical Physics Letters 363 (2002) 567–572 www.elsevier.com/locate/cplett * Corresponding author. Fax: +49-351-4659-440. E-mail address: e.borowiak@ifw-dresden.de (E. Borowiak- Palen). 0009-2614/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved PII:S0009-2614(02)01253-8