Heterofullerenes and Heteronanotubes

Heterofullerenes/Heteronanotubes are nanostructures in which one or more of the carbon atoms are substituted by a heteroatom - for example N or B. In this sense, heterofullerene formation is a kind of 'on-ball' doping of the fullerene cage or 'on-tube' doping of the nanotube.

The IFW activities in our Spectroscopy group concentrate on the one hand on the production and purification of B-doped SWCNT, BCN-SWCNT as well as multi wall BN-nanotubes. On the other hand we perform a detailed analysis of the electronic optical and vibronic properties of heterofullerenes (C₅₉N) and of these heteronanotubes using state of the art high energy spectroscopy (EELS, PES, XAS) as well as optical spectroscopy. Important open scientific question addressed in detail are the charge localization at the substitutional site, the binding energy of excitonic states, the charge transfer, ....
Some of the highlights of this work include studies of :

• Heterofullerenes C₅₉N:

• In the solid state it forms the dimer (C₅₉N)₂ where the two monomers are linked at the nearest neighbor of N at the hexagon fusion by one intermolecular bond. The electron density distribution for the dimer is shown below.

  

• We are using photoemission spectroscopy, electron energy-loss spectroscopy in transmission, high resolution energy-loss spectroscopy (HREELS) and x-ray absorption spectroscopy as well as optical spectroscopy to study the vibrational and electronic properties (excitons, occupied and unoccupied electronic states) of pure (C₅₉N)₂ and its K-intercalated compounds. The latter are examples of combinational doping (on-ball doping plus intercalation).
  

• Multi wall BN nanotubes and single wall BCN nanotubes and B-doped and N-doped nanotubes:

• Production and characterization the structural and electronic and vibronic properties of multi wall - BN Nanotubes

• 

• Production and characterization of the structure, stoichiometry, electronic and vibronic properties of BCN-, B-doped and N-doped nanotubes
• In addition we are using electron energy-loss spectroscopy in transmission and x-ray absorption spectroscopy as well as optical spectroscopy to study the vibrational and electronic properties (excitons, occupied and unoccupied electronic states) of K-intercalated heterofullerene/heteronanotube compounds. The latter are examples of combinational doping (substitutional doping plus intercalation).

• SiC nanotubes and nanofibers:

• Production and characterization the structural and electronic and vibronic properties of SiC nanotubes and nanofibers produced by a high temperature substitution reaction of carbon nanotubes.

• 

Some of the publications resulting from this work are listed below. If you'd like a copy of any of these or more information about our work, please contact Thomas Pichler.

Literature:

• M.H. Ruemmeli, E. Borowiak-Palen, T. Gemming, M. Knupfer, K. Biedermann, R.J. Kalenczuk, T. Pichler
  On the formation process of silicon carbide nanophases via hydrogenated thermally induced templated synthesis
  Applied Physics A 80 (2005) Nr. 8, S. 1653-1656
  
• E. Borowiak-Palen, M.H. Ruemmeli, T. Gemming, M. Knupfer, K. Biedermann, A. Leonhardt, T. Pichler, R.J. Kalenczuk
  Bulk synthesis of carbon-filled silicon carbide nanotubes with a narrow diameter distribution
  Journal of Applied Physics 97 (2005) Nr. 5, S. 56102/1-3
• E. Borowiak-Palen, M.H. Ruemmeli, M. Knupfer, G. Behr, K. Biedermann, T. Gemming, R.J. Kalenczuk, T. Pichler
  Bulk quantity and physical properties of boron nitride nanocapsules with a narrow size distribution
  Carbon 43 (2005) Nr. 3, S. 615-621
  
• G.G. Fuentes, E. Borowiak-Palen, M. Knupfer, T. Pichler, J. Fink, L. Wirtz, A. Rubio
  Formation and electronic properties of BC3 single-wall nanotubes upon boron substitution of carbon nanotubes
  Physical Review B 69 (2004) Nr. 24, S. 245403/1-6
  
• E. Borowiak-Palen, T. Pichler, A. Graff, R.J. Kalenczuk, M. Knupfer, J. Fink
  Synthesis and electronic properties of B-doped single wall carbon nanotubes
  Carbon 42 (2004) 1123–1126
  
• E. Borowiak-Palen, T. Pichler, G.G. Fuentes, A. Graff, R.J. Kalenczuk, M. Knupfer and J. Fink
  Efficient production of B-substituted single wall carbon nanotubes
  Chem. Phys. Lett. 378, 516 (2003)
  
• E. Borowiak-Palen, T. Pichler, G.G. Fuentes, B. Bendjemil, X. Liu, A. Graff, G. Behr, R. J. Kalenczuk, M. Knupfer and J. Fink
  Infrared response of multiwalled boron nitride nanotubes
  Chem. Comm. (2003) Nr. 1, S. 82-83
  
• G.G. Fuentes, Ewa Borowiak-Palen, T. Pichler, X. Liu, A. Graff, R.J. Kalenczuk, M. Knupfer, J. Fink
  Electronic structure of multiwall boron nitride nanotubes
  Phys. Rev. B 67, 035429 (2003)
  
• M.R.C. Hunt, T. Pichler, L. Siller, P.A. Brühwiler, M.S. Golden, N. Tagmatarchis, K. Prassides, P. Rudolf
  Final-state interference effects in valence band photoemission of (C₅₉N)₂
  Physical Review B 66 (2002) Nr. 19, S. 193404/1-4.
  
• M. Krause, S. Baesfischlmair, R. Pfeiffer, W. Plank, T. Pichler, H. Kuzmany, N. Tagmatarchis, K. Prassides
  Thermal stability and high-temperature graphitization of bisazafullerene (C₅₉N)₂ as studied by IR and Raman spectroscopy
  Journal of Physical Chemistry 105 (2001) Nr. 48, S. 11964-11969
  
• W. Plank, T. Pichler, H. Kuzmany
  The phases of quenched fullerenes RbC₆₀
  Synthetic Metals 121 (2001) Nr. 1-3, S. 1107-1108
  
• T. Pichler, H. Kuzmany, N. Tagmatarchis, K. Prassides
  Phases for the azafullerides Rb_xC₅₉N
  Physical Review B 63 (2001) Nr. 14, S. 140301/1-4
  
• J.M. Auerhammer, T. Kim, M. Knupfer, M.S. Golden, J. Fink, N. Tagmatarchis, K. Prassides
  Vibrational and electronic excitations of (C₅₉N)₂
  Solid State Communications 117, 697-701 (2001)
  
• S. Haffner, T. Pichler, M. Knupfer, B. Umlauf, R. Friedlein, M. S. Golden, J. Fink, M. Keshavarz-K., C. Bellavia-Lund, A. Sastre, J.-C. Hummelen, and F. Wudl
  The electronic structure of (C₅₉N)₂ from high energy spectroscopy
  Eur. Phys. J. B 1 (1998) 1
  
• T. Pichler, M. Knupfer, M. S. Golden, J. Fink, J. Winter, M. Haluska, H. Kuzmany, M. Keshavarz-K,
  C. Bellavia-Lund, A. Sastre, J.-C. Hummelen, and F. Wudl
  The electronic structure of polymerized fullerenes and dimerized heterofullerenes
  Appl. Phys. A 64 (1997) 301
  
• T. Pichler, M. Knupfer, R. Friedlein, S. Haffner, B. Umlauf, M. S. Golden, O. Knauff, H.-D. Bauer, J. Fink, M. Keshavarz-K, C. Bellavia-Lund, A. Sastre, J.-C. Hummelen, and F. Wudl
  The dielectric function of dimerised C₅₉N
  Synth. Metals 86 (1997) 2313
  
• T. Pichler, M. Knupfer, M. S. Golden, S. Haffner, R. Friedlein, J. Fink, W. Andreoni, A. Curioni, M. Keshavarz-K, C. Bellavia-Lund, A. Sastre, J.-C. Hummelen, and F. Wudl
  On-ball doping of fullerenes: the electronic structure of C₅₉N dimers from experiment and theory
  Phys. Rev. Lett. 78 (1997) 424