W.M. Keck Laboratory for Atomic Imaging and Manipulation: News & Events

[05/06/2013] CONGRATULATIONS - Taoran Cui's doctoral thesis entitled "Structure and Physical Properties of Torsional Carbon Nanotube Devices by Electron Diffraction and Microscopy" passed final examination.

[04/04/2012] CONGRATULATIONS - Zheng Ren's doctoral thesis entitled "Fabrication and Characterization of Aligned Titania Nanowire Films for Solar Cell Applications" passed final examination.

[11/07/2011] A paper on the direct measurement of the friction between and shear moduli of shells of double-shell carbon nanotubes with in situ electron diffraction and imaging is published in Physics Review Letters. [L. Lin, T. Cui, L.-C. Qin, and S. Washburn, Phys. Rev. Lett. 107, 206101 (2011).]

[09/05/2011] A paper on the structure and performance of graphene-carbon nanotube based supercapacitors is published which reports the highest energy densities of 63 Wh/kg and 156 Wh/kg in organic and ionic liquid electrolytes, repectively. [Q. Cheng, J. Tang, J. Ma, H. Zhang, N. Shinya, and L.-C. Qin, Phys. Chem. Chem. Phys. 13, 17615-17624 (2011).] (Press Release)

[05/06/2011] Congratulations - Zheng Ren presented his thesis proposal and passed the Preliminary Examination.

[05/04/2011] CONGRATULATIONS - Benjamin Wang's thesis "Fabrication and Characterization of Nanostructured Copper Oxide and Zinc Oxide Thin Films for Photovoltaic Applications" passed examination and is awarded Highest Honor.

[03/30/2011] CONGRATULATIONS - Letian Lin's doctoral thesis entitled "Fabrication, Structure and Properties of a Single Carbon Nanotube-Based Nano-Electromechanical System" passed final examination.

[12/04/2010] Three papers are presented at the Materials Research Society Fall Meeting held in Boston November 29 - December 3.

J. Yuan, H. Zhang, N. Shinya, J. Tang, L.-C. Qin: HfC nanowire point electron source. (W9.36)

J. Ma, J. Tang, Q. Cheng, H. Zhang, N. Shinya, L.-C. Qin: Spinning conductive carbon nanotube fibers by dielectrophoresis. (Y3.18)

Q. Cheng, J. Ma, H. Zhang, N. Shinya, J. Tang, L.-C. Qin: Nano-flowers MnO₂ coated graphene composite electrodes for energy storage devices. (Y14.4)

[12/01/2010] A paper on a systematic electron diffraction method for determining the chiral indices of multiwalled carbon nanotubes is publishewd in Ultramicroscopy. [H. Deniz, A. Derbakova, and L.-C. Qin, Ultramicroscopy 111, 66 (2010).]

[09/08/2010] A paper on the fabrication and characerization of LaB₆ nanowire-based field-emission point electron source is published in Nano Letters. (Press Release)

[09/03/2010] Congratulations - Benjamin Wang is offered a 2010 NC Space Grant Undergraduate Research Fellowship Award.

[12/02/2009] Letian Lin presents a paper at the Materials Research Society Fall Meeting held in Boston November 30 - December 4.

 L. Lin, L.-C. Qin, S. Washburn, S. Paulson: Electrical resistance of single-wall carbon nanotubes with determined chiral indices.

[10/13/2009] Congratulations - Letian Lin presented his thesis proposal and passed the Preliminary Examination.

[05/15/2009] Benjamin Wang has won a UNC SURF scholarship and a NIMS Internship - he will be working in the 1D Nanomaterials Research Group at the National Institute for Materials Science (NIMS) in Tsukuba, Japan.

[05/06/2009] CONGRATULATIONS - Anya Derbakova's thesis "Simulation and Analysis of Carbon Nanotube Diffraction Patterns" passed examination and is awarded Highest Honor.

[11/28/2007] Three papers are presented at the Materials Research Society Fall Meeting held in Boston November 26 - 30.

L.-C. Qin, H. Deniz: Measuring the chirality of multiwalled carbon nanotubes - each and every shell.

J. Tang, H. Zhang, P. Zhu, L.-C. Qin: Tensile modulus of carbon nanotube nano-fibers produced by dielectrophoresis.

D. Chen, T. Sasaki, J. Tang, L.-C. Qin: Deformation and its effects on the electronic structure of the SWCNT bundle.

[11/20/2007] CONGRATULATIONS - Hakan Deniz's doctoral thesis entitled "Electron Diffraction and Microscopy Study of Nanotubes and Nanowires" passed examination.

[08/08/2007] Three papers are presented at the Microscopy and Microanalysis Annual Conference held in Fort Lauderdale, Florida, August 6 - 9.

L.-C. Qin, Z. Liu, Q. Zhang, H. Deniz: Determination of the chirality of carbon nanotubes by electron diffraction. (Invited)

H. Deniz, L.-C. Qin, H. Zhang, J. Tang: An electron diffraction RDF study of amorphous boron nanowires.

H. Zhang, J. Tang, Q. Zhang, O. Zhou, L.-C. Qin: An in situ TEM study of field emission of electrons from LaB6 nanowires.

[06/05/2007] JEM-100CX is up and running in the new laboratory.

[05/22/2007] Both JEM-2010F and JEM-100CX are moved into the new laboratory.

[05/07/2007] Microscopes are shut down in making preparations for moving into the new laboratory - B26 Chapman Hall.

[12/29/2006] "Field emission of electrons from a Cs-doped single carbon nanotube of known chiral indices" is published - it reports a reduction of the work function of a multiwalled carbon nanotube with the chirality of each shell determined. [G. Zhao, Q. Zhang, H. Zhang, G. Yang, O. Zhou, L.-C. Qin, and J. Tang, Appl. Phys. Lett. 89, 263113 (2006).]

[12/15/2006] Farewell - Qi leaves UNC to join Penn State. Wishing her the best of luck in her pursuit of successes in electron microscopy of materials.

[12/08/2006] Congratulations! Hakan Deniz presented and passed his prelim exam today.

[11/30/2006] When the diameter of a TiO2 nanotube is reduced, its band gap will shrink as demonstrated in the paper "Reduction in the electronic band gap of titanium oxide nanotubes". [Z. Liu, Q. Zhang, and L.-C. Qin, Solid State Communications 141, 168 (2007).]

[11/27/2006] MRS Fall Meeting - Two papers are presented at the Materials Research Society Fall Meeting held in Boston this week:

L.-C. Qin, Z. Liu, Q. Zhang, G. Zhao, H. Deniz, J. Tang: Determination of the chiral indices of carbon nanotubes.

J. Tang, L.-C. Qin, X. Gu, K. Lu: Structural transitions of an Al-based metallic glass under high pressure.

[11/09/2006] CONGRATULATIONS - Han Zhang presented and defended successfully today his doctoral thesis entitled "Synthesis, Characterization, and Field Emission Properties of Rare-Earth Hexaboride Nanowires".

[11/08/2006] "Fabrication and characterization of single carbon nanotube emitters as point electron sources" is published. [G. Zhao, J. Zhang, Q. Zhang, H. Zhang, O. Zhou, L.-C. Qin, and J. Tang, Appl. Phys. Lett. 89, 193113 (2006).]

[09/04/2006] IMC 16 - Four papers are presented at the 16th International Microscopy Congress held this week in Sapporo, Japan:

L.-C. Qin, Q. Zhang, Z. Liu: Obtaining the chiral indices of carbon nanotubes by electron diffraction.

J. Tang, Q. Zhang, G. Yang, O. Zhou, L.-C. Qin: Fabrication of AFM probes by assembling single-walled carbon nanotubes and magnetic nanowires using dielectrophoresis.

H. Zhang, J. Tang, Q. Zhang, L.-C. Qin: LaB6 single-crystalline nanowiress for use as a field-emission point electron source.

Q. Zhang, J. Tang, Z. Liu, H. Zhang, L.-C. Qin, X. Zhao, Y. Ando: Atomic structure characterization of a multi-walled carbon nanotube by nanobeam electron diffraction under Koehler illumination.

[08/24/2006] Farewell - Gongpu Zhao is heading for Tempe, Arizona to take up a postdoctoral position in the Department of Physics and Astronomy at Arizona State University.

[07/10/2006] CONGRATULATIONS - Gongpu Zhao presented and defended successfully today his doctoral thesis entitled "Fabrication, Structure, and Electron Emission of Single Carbon Nanotubes". Photograph with Exam Committee

[03/31/2006] Chengyan Xu presented a paper at the 231st National Meeting of the American Chemical Society held during this week in Atlanta, Georgia.

C.Y. Xu, L. Zhen, Q. Zhang, L. Yang, J. Tang, L.-C. Qin, Synthesis and characterization of ternary metal oxide nanowires.

[03/13/2006] Three papers are presented at the American Physical Society's March Meeting that is held this week (13 -17 March) in Baltimore, Maryland.

Z. Liu, L.-C. Qin: Determination of diameter, helicity, and handedness of carbon nanotubes by electron diffraction.

Q. Zhang, Z. Liu, L.-C. Qin, X. Zhao, Y. Ando, Structure determination of a nine-wall carbon nanotube by nanobeam electron diffraction.

G. Zhao, Q. Zhang, H. Zhang, G. Yang, J. Tang, O. Zhou, L.-C. Qin: Thermal field emission from an individual carbon nanotube.

[01/02/2006] Single-crystalline LaB₆ nanowires open a new opportunity to high performance point electron sources and their field emission characteristics are reported in a paper published in Advanced Materials. [H. Zhang, J. Tang, Q. Zhang, G. Zhao, G. Yang, J. Zhang, O. Zhou and L.-C. Qin, Adv. Mater. 18, 87 (2006).]

[12/20/2005] NIMS-UNC Workshop on Nanomaterials is held during 20-21 December at the National Institute for Materials Science (NIMS) in Tsukuba, Japan.

[11/29/2005] Two papers are presented at the Materials Research Society Fall Meeting that is held this week (28 Nov - 2 Dec).

H. Zhang, J. Tang, Q. Zhang, G. Zhao, G. Yang, J. Zhang, O. Zhou, L.-C. Qin: LaB6 nanowiress and their field emission properties.

J. Tang, T. Sasaki, L.-C. Qin: Transport properties of single-walled carbon nanotubes under pressure.

[09/21/2005] In order to achieve high performance field-emission point electron sources of lowest energy spread, low work function materials are required. We have fabricated successfully GdB₆ nanowires of work function 1.5 eV and also tested their field emission characteristics. [H. Zhang, Q. Zhang, G. Zhao, J. Tang, O. Zhou and L.-C. Qin, J. Am. Chem. Soc. 127, 13120 (2005).]

[08/17/2005] Two types of single-crystalline alkali titanate nanowires, sodium titanate (Na₂Ti₆O₁₃) and potassium hollandite (KTi₈O_16.5) nanowires, have been successfully synthesized and characterized using electron diffraction and electron microscopy. [C. Xu, Q. Zhang, H. Zhang, L. Zhen, J. Tang and L.-C. Qin, J. Am. Chem. Soc. 127, 11584 (2005).]

[08/01/2005] When achiral carbon nanotubes (of armchair or zigzag structure) are oriented at some specific angles relative to the incident electron beam, extinction of certain odd-indexed layer lines occurs and details are discussed in a recent publication. [Z. Liu and L.-C. Qin, Chem. Phys. Lett. 412, 399 (2005).]

[07/15/2005] While raft-like bundles of single-walled carbon nanotubes have often been called nanotuube ropes, we have studied, both experimentally and theoretically, the structure and energetics of twist ropes formed by single-walled carbon nanotubes - the results have just been published in Carbon. [Z. Liu and L.-C. Qin, Carbon 43, 2146 (2005).]

[07/05/2005] A new method has just been published for determining the handedness of the carbon shells in multiwalled nanotubes. It is experimentally feasible - all one needs to do is to rotate the nanotube axially and observe the azimuthal dependence of electron diffraction intensities. [Z. Liu and L.-C. Qin, Chem. Phys. Lett. 411, 291 (2005).]

[07/01/2005] The installation of JEM-2010F-FasTEM in the W.M. Keck Laboratory for Atomic Imaging and Manipulation is accepted.

[06/22/2005] A systematic study on the distribution of the atomic structure (diameter & helicity) of single-walled carbon nanotubes has just been published in Physical Review B. More than 120 individual carbon nanotubes have been examined and their chiral indices have been determined unambiguously. [Z. Liu, Q. Zhang and L.-C. Qin, Phys. Rev. B 71, 245413 (2005).]

[06/06/2005] A new paper has just been published in the Journal of The American Chemical Society reporting the successful synthesis and characterization of cerium hexaboride (CeB6) nanowires grown in the <001> direction. Being an excellent thermionic electron emitter, the successful synthesis of CeB6 nanowires offers an opportunity to produce better field electron emitters for point electron source applications. [H. Zhang, Q. Zhang, J. Tang and L.-C. Qin, J. Am. Chem. Soc. 127, 8002 (2005).]

[06/02/2005] Lu-Chang Qin presents an invited talk at the annual meeting of the American Crystallographic Association (ACA) held in Orlando, Florida.

L.-C. Qin and Z. Liu: Diffraction Symmetry and Structure Determination of Carbon Nanotubes.

[05/12/2005] IDE active vibration isolation system (AVIS) is installed to reduce the low frequency mechanical noise due to floor vibrations.

[05/02/2005] Nanobeam electron diffraction has also been applied to determine the chiral indices of multiwalled carbon nanotubes. In a paper published today in Applied Physics Letters, the procedure is outlined and a example of a quadruple-walled carbon nanotube is given as an illustration. The four shells have chiral indices [32,1], [26,24], [39,25], and [64,2]. All shells are seminconducting. [Z. Liu, Q. Zhang and L.-C. Qin, Appl. Phys. Lett. 86, 191903 (2005).]

[04/25/2005] It has been a long standing problem to determine the atomic structure of carbon nanotubes that is usually described  by the two crystallographic indices (chiral indices) [u,v] that define the perimeter vector on the graphene net ever since the concept of carbon nanotubes came into being in 1991. We have just developed a rapid and accurate method to determine the chiral indices [u,v] from a single electron diffraction pattern. The electron diffraction intensities on the three principal layer lines are found to be proportional to the square of the Bessel functions of orders v, u, and u+v, respectively. Since the intensity peaks of a Bessel function is unique to its specific order, this allows the direct reading of the chiral indices from a single electron diffraction of the nanotube of chiral indices [u,v]. Once the chiral indices of a carbon nanotube is determined, its metallicity can be told immediately: if u-v is divisiable of integer three, it is metallic; otherwise it is semiconducting. [Z. Liu and L.-C. Qin, Chem. Phys. Lett. 408, 75 (2005).]

Basing on these findings and thanks to the assistance in programming by Tao Wan of the University of Bristol, Nanotube Diffraction Simulator is now available on our web site (NDS).

[04/20/2005] Congratulations - Han Zhang presented his thesis proposal and passed the preliminary examination.

[04/07/2005] CONGRATULATIONS - Zejian Liu presented and defended successfully today his doctoral thesis entitled "Atomic Structure Determination of Carbon Nanotubes by Electron Diffraction".

[03/21/2005] The following papers are presented at the APS March Meeting held this week (21-25 March) in Los Angeles:

Z. Liu and L.-C. Qin: Accurate Determination of the Atomic Structure of Carbon Nanotubes by Electron Diffraction.

G. Yang, J. Tang, Q. Zhang, A. Parhat, B. Maynor, J. Liu, L.-C. Qin and O. Zhou: Rapid and Reproducible Fabrication of Nanotube/Nanowire AFM Probes by Dielectrophoresis.

[03/17/2005] While circular carbon nanotubes have been considered as an ideal structure, elliptical nanotubes represent the general morphology - circular nanotubes are a special case. We have studied the electron diffraction from elliptical carbon nanotubes, both theoretically and experimentally,  and found that (a) the chiral indices [u,v] can be determined using the method developed for circular nanotubes; (b) the symmetry is no longer always 2mm; and (c) eccentricity can be measured experimentally. [Z. Liu and L.-C. Qin, Chem. Phys. Lett. 406, 106 (2005).]

[03/09/2005] In addition to diameter and helicity, the handedness (right-handed or left-handed) of a carbon nanotube can also have strong effects on the properties of the carbon nanotube. In a recent paper that has just been published in Chemical Physics Letters, measurement of the handedness of single-walled carbon nanotubes is studied. It establishes that the electron diffraction pattern will change asymmetrically when the nanotube is twisted in opposite directions about its tubule axis and therefore the handedness of the nanotube can be obtained. [Z. Liu and L.-C. Qin, Chem. Phys. Lett. 405, 265 (2005).]

[03/02/2005] A new paper has just been published in the Journal of The American Chemical Society reporting the successful synthesis and characterization of lanthanum hexaboride (LaB6) nanowires grown in the <111> direction. Being an excellent thermionic electron emitter, the successful synthesis of LaB6 nanowires offers an opportunity to produce better field electron emitters for point electron source applications. [H. Zhang, Q. Zhang, J. Tang and L.-C. Qin, J. Am. Chem. Soc. 127, 2862 (2005).]

[01/02/2005] What is the symmetry of electron diffraction patterns from multiwalled carbon nanotubes? Still 2mm as in the case of single-walled carbon nanotubes? We have shown that this is not true in general. Under some special circumstances, the 2mm symmetry breaks down, retaining only the inversion center in the electron diffraction pattern governed by the Friedel's Law. [Z. Liu and L.-C. Qin, Chem. Phys. Lett. 402, 202 (2005).]