Funding OTKA T 049338 Alexander von Humboldt Foundation

1. The samples Resonant Raman scattering Depth sampling Tubes@Rice: Pulsed laser vaporization  SWCNT + Ni/Co catalyst  Refluxing with HNO3  SWCNT-COOH  Heating to 800 ºC  SWCNT Functionalization by modified Birch reduction [1]: Li + n NH3 Li+ + e- (NH3)n e- (NH3)n + C  C- + nNH3 C- + BzBr  BzC + Br- C- + BuI  BuC + I- C- + MeI  MeC + I- C- + HX  HC + X- (HX = H2O, NH3, CH3OH) The degree of functionalization (R+H)/100C was determined from TG-MS. 468 nm 531 nm 676 nm S33+S44 S33 M11 The samples are inhomogeneous average spectra selected for comparison with TG-MS [2] A complete spectrum Selectivity on tube type 468 nm 468 nm 531 nm 676 nm Lorentzian 676 nm 531 nm Gaussian Bz Bu Me Bz Bu Me ID/IG and ID/ID* increase with the degree of functionalization, as the change of the electronic structure is only minor. The ratio depends on the wavelength of the exciting laser, as in Ref. 3. If we substract the value measured in the pristine sample (arising from the defects of the pristine nanotube) the change is similar for both metallic and semiconducting nanotubes.  The reaction is not selective for tube type • No functional groups are visible andnanotubes are still in resonance. • Electronic structure is not collapsed due to functionalization. The same degree of functionalization leads to smaller changes in the electronic structure in the case of apolar alkyl groups than in the case of polar substituted phenyl groups [3]. Selectivity on tube diameter Explanation of the selectivity Most of the functionalization reactions are primarily selective to metallic tubes [7], as these tubes have the nonzero DOS at the Fermi level [8]. Birch-type alkylation begins with doping by excess Li, which fills both S11, S22 and M11[9].  The selectivity for metallic tubes is masked The charged nanotubes are dispersed in the liquid NH3 solution.  The size of the cavity in the bundle does not play a role. Carbanions having greater s-character are more stable.  Smaller diameter tubes are more reactive According to the RBM spectrum the small diameter semiconducting nanotubes react more readily. This is in accordance with NIR[4, 5] and Raman[6] spectroscopic measurements on alkylated HiPCO tubes. In the case of 531 nm and 676 nm laser excitation the change was obscured by the error. Raman spectra of functionalized carbon nanotubes G. Klupp, F. Borondics, R. Hackl*, K. Kamarás, E. Jakab**, S. Pekker Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Budapest, Hungary, e-mail: klupp@szfki.hu *Walther Meissner Institute, Bavarian Academy of Sciences and Humanities, Garching, Germany **Institute of Materials and Environmental Chemistry, Budapest, Hungary Funding OTKA T 049338 Alexander von Humboldt Foundation References [1]: F. Borondics, E. Jakab, S. Pekker: Journal of Nanoscience and Nanotechnology 7, 1551 (2007) [2]: H. Kataura, Y. Kumazawa, Y. Maniwa, I. Umezu, S. Suzuki, Y. Ohtsuka, Y. Achiba: Synth. Metals 103, 2555 (1999) [3]: C. Fantini, M. L. Usrey, M. S. Strano: J. Phys. Chem. C 111, 17941 (2007) [4]: Á. Pekker, D. Wunderlich, K. Kamarás, A. Hirsch: Phys. Stat. Sol. B 245, 1954 (2008) [5]: K. Németh, F. Borondics, E. Jakab, Á. Pekker, K. Kamarás, S. Pekker: Poster #5 on SIWAN 2008 [6]: M. Müller, J. Maultzsch, D. Wunderlich, A. Hirsch, C. Thomsen: Phys. Stat. Sol. B 244, 4056 (2007) [7]: K. Kamarás, Á. Pekker: Handbook of Nanoscience and Technology, Editors: A. V. Narlikar, Y. Y. Fu, Oxford University Press, 2009 [8]: M. S. Strano: J. Am. Chem. Soc.125, 16148 (2003) [9]: S. Kazaoui, N. Minami, R. Jacquemin, H. Kataura, Y. Achiba: Phys. Rev. B 69, 13339 (1999)