1 Lu Lu-Chang Qin Chang Qin IMR, Shenyang 07/12/07 IMR, Shenyang 07/12/07 Determination of the Determination of the Chirality Chirality of Carbon of Carbon Nanotubes Nanotubes - it is easy now it is easy now - W.M. Keck Laboratory for Atomic Imaging and Manipulation W.M. Keck Laboratory for Atomic Imaging and Manipulation Department of Physics and Astronomy and Department of Physics and Astronomy and Curriculum in Applied and Materials Sciences Curriculum in Applied and Materials Sciences University of North Carolina at Chapel Hill, USA University of North Carolina at Chapel Hill, USA Qin Lu-Chang 秦 禄昌 Lu Lu-Chang Qin Chang Qin IMR, Shenyang 07/12/07 IMR, Shenyang 07/12/07 Acknowledgements Acknowledgements Hakan Hakan Deniz Deniz Zejian Zejian Liu Liu Gongpu Gongpu Zhao Zhao Han Zhang Han Zhang Qi Qi Zhang Zhang W.M. Keck Foundation W.M. Keck Foundation UNC UNC AFOSR, DOE, AFOSR, DOE, Xintek Xintek
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Determination of the Determination of the ChiralityChiralityof Carbon of Carbon NanotubesNanotubes
-- it is easy now it is easy now --
W.M. Keck Laboratory for Atomic Imaging and ManipulationW.M. Keck Laboratory for Atomic Imaging and ManipulationDepartment of Physics and Astronomy andDepartment of Physics and Astronomy and
Curriculum in Applied and Materials SciencesCurriculum in Applied and Materials SciencesUniversity of North Carolina at Chapel Hill, USAUniversity of North Carolina at Chapel Hill, USA
Schematic showing the formation and definition of a single-walled carbon nanotube. The chiral indices (u,v) are related to diameter and helicity. For example, when u – v is divisible by 3, it is metallic, otherwise it is semiconducting.
Why Why ChiralityChirality ((u,vu,v) is Important?) is Important?
Properties of a CNT are Properties of a CNT are chiralitychirality--sensitive!sensitive!Precision of measurement matters!Precision of measurement matters!Electronic: Electronic: (u (u –– v) divisible by 3: Metallicv) divisible by 3: Metallic
SemiconductingSemiconducting SWNTsSWNTs of small diameterof small diameter–– Electronic absorptionElectronic absorption–– Emission transitionsEmission transitions–– Resonance Raman dataResonance Raman data
Precision Measurement is CrucialPrecision Measurement is Crucial
Properties of a CNT are Properties of a CNT are chiralitychirality--sensitive!sensitive!Precision of measurement matters!Precision of measurement matters!
Intensities appear on discrete lines (layer Intensities appear on discrete lines (layer lines) due to axial periodicity;lines) due to axial periodicity;On each layer line of order On each layer line of order ll, the , the intesnityintesnityis proportional to the square of Bessel is proportional to the square of Bessel function of order function of order ll;;When there is a mWhen there is a m--fold rotational fold rotational symmetry (m helices), the nonsymmetry (m helices), the non--extinction extinction reflections appear on layer line reflections appear on layer line mlml; ;
On the base line, there is one (v) helix parallel to a1 (blue), seven (u) helices parallel to a2 (orange), and eight (u+v) helices parallel to a3 (green). Example: [7,1]
Electron diffraction pattern of a single-walled carbon nanotube [17,2]. (a) Electron diffraction pattern. (b) Intensity line profile on layer line l1. (c) Intensity line profile on layer line l2.
Structure determination of a quadruple-walled carbon nanotube by electron diffraction. Three helicities exist in the tubule with two shells having the same helicity.
Chiral indices (Chiral indices (uu,,vv), ), metallicitymetallicity, diameter , diameter dd, and , and helicityhelicity of each shell of the carbon nanotube.of each shell of the carbon nanotube.
G. Zhao et al. Appl. Phys. Lett. 89, 263113 (2006).
SummarySummary A systematic method has A systematic method has been established to obtain been established to obtain the chiral indices (the chiral indices (u,vu,v) of ) of carbon nanotubes from their carbon nanotubes from their electron diffraction patterns. electron diffraction patterns.
1. L.-C. Qin, “Electron diffraction from cylindrical nanotubes”; J. Mater. Res. 9, 2450 (1994).2. L.-C. Qin, T. Ichihashi, S. Iijima, “On the measurement of helicity of carbon nanotubes”; Ultramicroscopy 67, 181 (1997).3. L.-C. Qin, S. Iijima, H. Kitaura, Y. Maniwa, S. Suzuki and Y. Achiba, “Helicity and packing of single-walled carbon
nanotubes studied by electron nanodiffraction”; Chem. Phys. Lett. 268, 101 (1997). 4. L.-C. Qin, “Measuring the true helicity of carbon nanotubes”; Chem. Phys. Lett. 297, 23 (1998).5. L.-C. Qin, “Helical diffraction from tubular structures”; Mater. Characterization 44, 407 (2000).6. L.-C. Qin, “Determining the Helicity of Carbon Nanotubes by Electron Diffraction”; in Progress in Transmission Electron
Microscopy 2: Applications in Materials Science. Eds. X.-F. Zhang and Z. Zhang, Springer Series in Surface Sciences Vol. 39, (Tsinghua University Press and Springer-Verlag, 2001) pp.73-104.
7. L.-C. Qin, “Diffraction and Imaging of Single Walled Carbon Nanotubes”; in Electron Microscopy of Nanotubes and Nanowires. Eds. Z.L. Wang and C. Hui. (Kluwer Academic Publisher, 2003) pp.1-41.
8. Z. Liu, L.-C. Qin, “Symmetry of electron diffraction from single-walled carbon nanotubes”, Chem. Phys. Lett. 400, 430 (2004).
9. Z. Liu, L.-C. Qin, “Breakdown of the 2mm symmetry of electron diffraction from multiwalled carbon nanotubes”, Chem. Phys. Lett. 402, 202 (2005).
10. Z. Liu, L.-C. Qin, “A practical approach to determine the handedness of single-walled carbon nanotubes”, Chem. Phys. Lett. 405, 205 (2005).
11. Z. Liu, L.-C. Qin, “Electron diffraction from elliptical nanotubes”; Chem. Phys. Lett. 406, 106 (2005).12. Z. Liu, L.-C. Qin, “A direct method to determine the chiral indices of carbon nanotubes”, Chem. Phys. Lett. 408, 75 (2005).13. Z. Liu, L.-C. Qin, “Measurement of handedness in multiwalled carbon nanotubes by electron diffraction”, Chem. Phys. Lett.
411, 291 (2005).14. Z. Liu, L.-C. Qin, “Extinction and orientational dependence of electron diffraction from single-walled carbon nanotubes”,
Chem. Phys. Lett. 412, 399 (2005).15. Z. Liu, Q. Zhang, L.-C. Qin, “Accurate structure determination of multiwalled carbon nanotubes by nondestructive
nanobeam electron diffraction”; Appl. Phys. Lett. 86, 191903 (2005).16. Z. Liu, Q. Zhang, L.-C. Qin, “Determination and mapping diameter and helicity of single-walled carbon nanotubes by
nanobeam electron diffraction”, Phys. Rev. B 71, 245413 (2005).17. L.-C. Qin, “Electron diffraction from carbon nanotubes”; Rep. Prog. Phys. 69, 2781 (2006).18. L.-C. Qin, “Determination of the chiral indices of carbon nanotubes by electron diffraction”; Phys. Chem. Chem. Phys. 9,