Imagine how much control over resultant properties you would have if you were able to deposit and maneuver individual atoms into predefined arrangements, en route toward a new material. This is fast becoming a reality, and is the realization of the ultimate in “bottom-up” materials design. Thus far, one is able to easily fabricate materials comprised of a small number of atoms, with features on the nanometer scale (10−9 m) – one-billionth of a meter. To put this into perspective, think of a material with dimensions approximately 1,000 times smaller than the diameter of a human hair follicle! As we will see, it is now even possible to push individual atoms around a surface using specialized techniques.


American Chemical Society PAMAM Dendrimers Isolate Pentagon Rule SWNT Array Nanoscale Building Block 
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References and Notes

  1. 1.
    A sampling of some intriguing applications that are already possible using nanomaterials include: self-cleaning fabrics (via TiO2 nanoparticles), automobile clearcoats that prevent scratches (PPG nanoparticle-based coatings), car wash solutions that prevent dirt from adhering to a painted surface, bandages that kill bacteria, drug-release agents and time-release biocidal coatings, and tennis balls that bounce twice as long as conventional balls.Google Scholar
  2. 2.
    Only US-based institutes/centers are listed here; for a more comprehensive list of worldwide nanotechnology efforts, see, a comprehensive listing of nanorelated websites hosted by the University of Singapore.
  3. 3.
    Now available online at Eric Drexler’s “Foresight Institute” website:
  4. 4.
    For details on the biological effects of CNTs, see: Liu, Z.; Cai, W.; He, L.; Nakayama, N.; Chen, K.; Sun, X.; Chen, X.; Dai, H. Nat. Nanotechnol. 2007, 2, 47, and references therein. The biological effects of dendritic polymers is described in Boas, U.; Heegaard, P. M. H. Chem. Soc. Rev. 2004, 33, 43, and references therein. Some comprehensive websites on the toxicological effects of nanostructures include: (a) OSHrisks.html; (b); (c); (d); (e)
  5. 5.
  6. 6. I. This image is a work of a United States Census Bureau employee, taken or made during the course of an employee’s official duties. As a work of the US Federal Government, the image is in the public domain.
  7. 7.
    Taniguchi, N. On the Basic Concept of NanoTechnology. Proc. ICPE 1974.Google Scholar
  8. 8.
  9. 9.
    For example, see Pishko, V. V.; Gnatchenko, S. L.; Tsapenko, V. V.; Kodama, R. H.; Makhlouf, S. A. J. Appl. Phys. 2003, 93, 7382.Google Scholar
  10. 10.
    For an excellent review of transition metal nanocluster formation and nomenclature, as well as the difference between colloids and nanoclusters, see Finke, R. G. Transition Metal Nanoclusters in Metal Nanoparticles: Synthesis, Characterization, and Applications, Dekker: New York, 2002.Google Scholar
  11. 11.
    For example, there is a 500% rate difference for the photoreduction of CO2 using 10 different samples of Pdn colloids: Wilner, I.; Mendler, D. J. Am. Chem. Soc. 1989, 111, 1330. Also, see Kohler, J. U.; Bradley, J. S. Catal. Lett. 1997, 45, 203, wherein they describe a 670% variation in the rate of hydrogenation with PVP-protected Ptn colloids (due to a widely dispersed composition, with varying numbers of surface Cl groups).Google Scholar
  12. 12.
    Though quantum dots are typically thought of as 0D nanostructures, quantum confinement effects are also exhibited in 1D nanowires and nanorods. Buhro and coworkers have studied the effect on both size and shape on quantum confinement (Yu, H.; Li, J.; Loomis, R. A.; Wang, L.-W.; Buhro, W. E. Nature Mater. 2003, 2, 517). Their work provides empirical data to back up the theoretical order of increasing quantum confinement effects: dots (3D confinement) > rods > wires (2D confinement) > wells (1D confinement). For an example of an interesting nanostructure comprised of both a nanorod and nanodot, see: Mokari, T.; Sztrum, C. G.; Salant, A.; Rabani, E.; Banin, U. Nature Mater. 2005, 4, 855.Google Scholar
  13. 13.
    (a) Lewis, J. Chem. Br. 1988, 24, 795. (b) Deeming, A. J. Adv. Organomet. Chem. 1986, 26, 1.Google Scholar
  14. 14.
    Shown from left to right are (a) Pd nanoclusters supported on hydroxyapatite: Mori, K.; Hara, T.; Mizugaki, T.; Ebitani, K.; Kaneda, K. J. Am. Chem. Soc. 2004, 126, 10657. (b) Copper nanoclusters: Williams, G. L.; Vohs, J. K.; Brege, J. J.; Fahlman, B. D. J. Chem. Ed. 2005, 82, 771.Google Scholar
  15. 15.
    Huang, J.; Kunitake, T.; Onoue, S.-Y. Chem. Commun. 2004, 1008.Google Scholar
  16. 16.
    Scher, E. C.; Manna, L.; Alivisatos, A. P. Philos. Trans. R. Soc. Lond. A. 2003, 361, 241.CrossRefGoogle Scholar
  17. 17.
    Shown is a Ti/O/C nanopowder with individual nanosized grains: Leconte, Y.; Maskrot, H.; Herlin-Boime, N.; Porterat, D.; Reynaud, C.; Gierlotka, S.; Swiderska-Sroda, A.; Vicens, J. J. Phys. Chem. B 2006, 110, 158.Google Scholar
  18. 18.
    Shown are submicron particulates (with some nanoparticles also present) of aluminum oxide: Williams, G. L.; Vohs, J. K.; Brege, J. J.; Fahlman, B. D. J. Chem. Ed. 2005, 82, 771.Google Scholar
  19. 19.
    For a thorough review of surface plasmon resonance, see Kelly, K. L.; Coronado, E.; Zhao, L. L.; Schatz, G. C. J. Phys. Chem. B 2003, 107, 668.Google Scholar
  20. 20.
    Mie, G. Ann. Phys. 1908, 25, 377. This theory represents the exact solution to Maxwell’s equations for a sphere. For details on recent theories to describe scattering from nonspherical nanostructures, see Reference [15], and the references therein.Google Scholar
  21. 21.
    Haes, A. J.; Stuart, D. A.; Nie, S.; Duyne, R. P. V. J. Fluoresc. 2004, 14, 355.CrossRefGoogle Scholar
  22. 22.
    For more information/precedents on quantum confinement effects for metallic nanoclusters, see: (a) Rao, C. N. R.; Kulkarni, G. U.; Thomas, P. J.; Edwards, P. P. Chem. Soc. Rev. 2000, 29, 27. (b) Mohamed, M. B.; Volkov, V.; Link, S.; El-Sayed, M. A. Chem. Phys. Lett. 2000, 317, 517. (c) Huang, T.; Murray, R. W. J. Phys. Chem. B 2001, 105, 12498. (d) Link, S.; Beeby, A.; FitzGerald, S.; El-Sayed, M. A.; Schaaff, T. G.; Whetten, R. L. J. Phys. Chem. B 2002, 106, 3410. (e) Empedocles, S.; Bawendi, M. Acc. Chem. Res. 1999, 32, 389. (f) El-Sayed, M. A. Acc. Chem. Res. 2001, 34, 257. (g) Zheng, J.; Petty, J. T.; Dickson, R. M. J. Am. Chem. Soc. 2003, 125, 7780. (h)Schaaff, T. G.; Shafigullin, M. N.; Khoury, J. T.; Vezmar, I.; Whetten, R. L.; Cullen, W. G.; First, P. N.; Gutierrez-Wing, C.; Ascensio, J.; Jose-Yacaman, M. J. J. Phys. Chem. B 1997, 101, 7885.Google Scholar
  23. 23.
    (a) Synthesis of the Iridium complex is reported in: Finke, R. G.; Lyon, D. K.; Nomiya, K.; Sur, S.; Mizuno, N. Inorg. Chem. 1990, 29, 1784. (b) Aiken, J. D.; Lin, Y.; Finke, R. G. J. Mol. Catal. A 1996,114,29.Google Scholar
  24. 24.
    For a detailed discussion of the mechanistic steps, see: Besson, C.; Finney, E. E.; Finke, R. G. J. Am. Chem. Soc. 2005, 127, 8179, and references therein.Google Scholar
  25. 25.
    For a thorough recent review on nanostructural growth via coprecipitation of multiple species (and ways to synthesize/stabilize 0D nanostructures), consult: Cushing, B. L.; Kolesnichenko, V. L.; O’Connor, C. J. Chem. Rev. 2004, 104, 3893.Google Scholar
  26. 26.
    A derivation and full explanation of cluster “magic numbers” is given by: Teo, B. K.; Sloane, N. J. A. Inorg. Chem. 1985, 24, 4545.Google Scholar
  27. 27.
    Finke, R. G. in Metal Nanoparticles: Synthesis, Characterization, and Applications, Feldheim, D. L.; Foss, C. A. eds., Dekker: New York, 2002. Crooks and coworkers determined that a closed-shell metallic nanocluster of Au55 has a diameter of 1.2 nm: Kim, Y.-G.; Oh, S.-K.; Crooks, R. M. Chem. Mater. 2004, 16, 167.Google Scholar
  28. 28.
    Kroto, H. W.; Heath, J. R.; O’Brien, S. C.; Curl, R. F.; Smalley, R. E. Nature 1985, 318, 162.CrossRefGoogle Scholar
  29. 29.
    The irradiation of C60 with light in the presence of O2 causes the formation of reactive singlet oxygen (1 O2 ); for example, see Jensen, A. W.; Daniels, C. J. Org. Chem. 2003, 68, 207.Google Scholar
  30. 30.
    Smalley and Curl named this structure after Buckminster Fuller, for his discovery of geodesic domes.Google Scholar
  31. 31.
    For an interesting book on the history of other serendipitous discoveries in science, see Roberts, R. M. Serendipity: Accidental Discoveries in Science, Wiley: New York, 1989.Google Scholar
  32. 32.
    Kroto, H. Nanotechnology 1992, 3, 111. A lecture given in the same title is also available as an audio file from
  33. 33.
    (a) Kriitschmer. W.; Lamb. L. D.; Fostiropoulos, K.; Huffman. D. R. Nature 1990, 347, 354. (b) Kratschmer, W.; Fostiropoulos, K.; Huffman, D. R. Chem. Phys. Lett. 1990, 170, 167. (c); a company that manages rights to fullerene production technology.
  34. 34.
    Manolopoulos, D. E. Chem. Phys. Lett. 1992, 192, 330.CrossRefGoogle Scholar
  35. 35.
    Sitharaman, B.; Bolskar, R. D.; Rusakova, I.; Wilson, L. J. Nano Lett. 2004, 4, 2373.CrossRefGoogle Scholar
  36. 36.
    Tanigaki, K.; Ebbesen, T. W.; Saito, S.; Mizuki, J.; Tsai, J. S.; Kubo, Y.; Kuroshima, S. Nature 1991, 352,222.CrossRefGoogle Scholar
  37. 37.
    Zakharian, T. Y.; Seryshev, A.; Sitharaman, B.; Gilbert, B. E.; Knight, V.; Wilson, L. J. J. Am. Chem. Soc. 2005, 127, 12508.CrossRefGoogle Scholar
  38. 38.
    Ewels, C. P. Nano Lett. 2006, 6, 890.CrossRefGoogle Scholar
  39. 39.
    Smalley, R. E. Acc. Chem. Res. 1992, 25, 98.CrossRefGoogle Scholar
  40. 40.
    Heath, J. R. ACS Symp. Ser. 1992, 481, 1.CrossRefGoogle Scholar
  41. 41.
    (a) V. Z. Mordkovich, V. Z.; Umnov, A. G.; Inoshita, T.; Endo, M. Carbon 1999, 37, 1855. (b) Mordkovich, V. Z. Chem. Mater. 2000, 12, 2813.Google Scholar
  42. 42.
    Sygula, A.; Rabideau, P. W. J. Am. Chem. Soc. 1999, 121, 7800.CrossRefGoogle Scholar
  43. 43.
    Gluch, K.; Feil, S.; Matt-Laubner, S. M.; Echt, O.; Scheier, P.; Mark, T. D. J. Phys. Chem. A 2004, 108,6990.CrossRefGoogle Scholar
  44. 44.
    Wang, C.-R.; Shi, Z.-Q.; Wan, L.-J.; Lu, X.; Dunsch, L.; Shu, C.-Y.; Tang, Y.-L.; Shinohara, H. J. Am. Chem. Soc., 2006, 128, 6605.CrossRefGoogle Scholar
  45. 45.
    Gan, L.-H.; Wang, C.-R. J. Phys. Chem. A 2005, 109, 3980.CrossRefGoogle Scholar
  46. 46.
    (a) Yonezawa, T.; Onoue, S.-Y.; Kimizuka, N. Langmuir 2000, 16, 5218. (b) Yonezawa, T.; Onoue, S.-Y.; Kimizuka, N. Chem. Lett. 2002, 528.Google Scholar
  47. 47.
    Crooks, R. M.; Zhao, M.; Sun, L.; Chechik, V.; Yeung, L. K. Acc. Chem. Res. 2001, 34, 181, and references therein. The first precedent for the use of poly(propylene imine) (PPI) dendrimers is: Floriano, P. N.; Noble, C. O.; Schoonmaker, J. M.; Poliakoff, E. D.; McCarley, R. L. J. Am. Chem. Soc. 2001, 123, 10545. This also contains many useful references for early precedents for metal@PAMAM nanocomposites.Google Scholar
  48. 48.
    For an example of trimetallic nanoparticle synthesis (using a nondendritic host), see: Henglein, A. J. Phys. Chem. B 2000, 104, 6683.Google Scholar
  49. 49.
    Schaak, R. E.; Sra, A. K.; Leonard, B. M.; Cable, R. E.; Bauer, J. C.; Han, Y.-F.; Means, J.; Teizer, W.; Vasquez, Y.; Funck, E. S. J. Am. Chem. Soc. 2005, 127, 3506.CrossRefGoogle Scholar
  50. 50.
    (a) Garcia-Martinez, J. C.; Crooks, R. M. J. Am. Chem. Soc. 2004, 126, 16170-16178. (b) Garcia-Martinez, J. C.; Scott, R. W. J.; Crooks, R. M. J. Am. Chem. Soc. 2003, 125, 11190-11191. (c) Kim, Y.-G.; Garcia-Martinez, J. C.; Crooks, R. M. Langmuir 2005, 21, 5485-5491.Google Scholar
  51. 51.
    (a) Kamata, K.; Lu, Y.; Xia, Y. J. Am. Chem. Soc. 2003, 125, 2384. (b) Marinakos, S. M.; Shultz, D. A.; Feldheim, D. L. Adv. Mater. 1999, 11, 34. (c) Chah, S.; Fendler, J. H.; Yi, J. J. Colloid Interface Sci. 2002, 250, 142. (d) Marinakos, S. M.; Novak, J. P.; Brousseau, L. C., III; House, A. B.; Edeki, E. M.; Feldhaus, J. C.; Feldheim, D. L. J. Am. Chem. Soc. 1999, 121, 8518.Google Scholar
  52. 52.
    Chen, M.; Gao, L. Inorg. Chem. 2006, 45, 5145.CrossRefGoogle Scholar
  53. 53.
    Yin, Y.; Rioux, R. M.; Erdonmez, C. K.; Hughes, S.; Somorjai, G. A.; Alivisatos, A. P. Science 2004, 304,711.CrossRefGoogle Scholar
  54. 54.
    Sun, S.; Zeng, H. J. Am. Chem. Soc. 2002, 124, 8204. Other examples of solution-phase growth of oxide, and other compound 0D nanostructures (including quantum dots) are: (a) Strable, E.; Bulte, J. W. M.; Moskowitz, B.; Vivekanandan, K.; Allen, M.; Douglas, T.Chem. Mater. 2001, 13, 2201. (b) Frankamp, B. L.; Boal, A. K.; Tuominen, M. T.; Rotello, V. M. J. Am. Chem. Soc. 2005, 127,9731. (c) Lemon, B. I.; Crooks, R. M. J. Am. Chem. Soc. 2000, 122, 12886. (d) Hanus, L. H.; Sooklal, K.; Murphy, C. J.; Ploehn, H. J. Langmuir 2000, 16, 2621.Google Scholar
  55. 55.
    Juttukonda, V.; Paddock, R. L.; Raymond, J. E.; Denomme, D.; Richardson, A. E.; Slusher, L. E.; Fahlman, B. D. J. Am. Chem. Soc. 2006, 128, 420.CrossRefGoogle Scholar
  56. 56.
    It should be noted that in addition to solution-phase methods, quantum dots are frequently synthesized using molecular-beam epitaxy or other vapor-phase technique. For example, see: Wang, X. Y.; Ma, W. Q.; Zhang, J. Y.; Salamo, G. J.; Xiao, M.; Shih, C. K. Nano Lett. 2005, 5, 1873, and references therein.Google Scholar
  57. 57.
    (a) Decher, G.; Hong, J. D. Makromol. Chem. Macromol. Symp. 1991, 46, 321. (b) Decher, G.; Hong, J. D.; Schmitt, J. Thin Solid Films 1992, 210, 831. For a recent review of electrostatic LbL growth, see: Hammond, P. T. Adv. Mater. 2004, 16, 1271.Google Scholar
  58. 58.
    Adamantyl groups were used on the periphery of the dendrimers since they strongly interact with cyclodextrins. For example, see: Rekharsky, M. V.; Inoue, Y. Chem. Rev. 1998, 98, 1880-1901.Google Scholar
  59. 59.
    The difference between nanocars and nanotrucks has been described as the former is only able to transport itself, whereas a nanotruck is able to accommodate a load.Google Scholar
  60. 60.
    (a) Shirai, Y.; Osgood, A. J.; Zhao, Y.; Kelly, K. F.; Tour, J. M. Nano Lett. 2005, 5, 2330. (b) Shirai, Y.; Osgood, A. J.; Zhao, Y.; Yao, Y.; Saudan, L.; Yang, H.; Chiu, Y.-H.; Alemany, L. B.; Sasaki, T.; Morin, J.-F.; Guerrero, J. M.; Kelly, K. F.; Tour, J. M. J. Am. Chem. Soc. 2006, 126, 4854.Google Scholar
  61. 61.
    (a) Iijima, S. Nature 1991, 354, 56 (first report of MWNTs). (b)Iijima, S. Nature 1993, 363, 603 (SWNT co-precedent). (c) Bethune, D. S.; Kiang, C. H.; Devries, M. S.; Gorman, G.; Savoy, R.; Vazquez, J.; Beyers, R. Nature 1993, 363, 605 (SWNT co-precedent).Google Scholar
  62. 62.
    The term graphene designates a single layer of carbon atoms packed into hexagonal units. Though this structure is used to describe properties of many carbonaceous materials (e.g., CNTs, graphite, fullerenes, etc.), this planar structure is thermodynamically unstable relative to curved structures such as fullerenes, nanotubes, and other structures found in carbon soot. As such, the isolation of single graphene sheets has only recently been reported through exfoliation from a high purity graphite crystal: Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. Science 2004, 306, 666.Google Scholar
  63. 63.
    (a) The SEM image (low-resolution and high-resolution) of 9,10-antraquinone nanorods is reproduced with permission from (copyright 2004 American Chemical Society): Liu, H.; Li, Y.; Xiao, S.; Li, H.; Jiang, L.; Zhu, D.; Xiang, B.; Chen, Y.; Yu, D. J. Phys. Chem. B 2004, 108, 7744. (b) The SEM image of GaP-GaAs nanowires is reproduced with permission from (copyright 2006 American Chemical Society): Verheijen, M. A.; Immink, G.; de Smet, T.; Borgstrom, M. T.; Bakkers, E. P. A. M. J. Am. Chem. Soc. 2006, 128, 1353. (c) The SEM image of carbon nanotubes is reproduced with permission from (copyright 2001 American Chemical Society): Chiang, I. W.; Brinson, B. E.; Smalley, R. E.; Margrave, J. L.; Hauge, R. H. J. Phys. Chem. B 2001, 105, 1157. (d) The SEM image of TiO2 nanofibers is reproduced with permission from (copyright 2006 American Chemical Society): Ostermann, R.; Li, D.; Yin, Y.; McCann, J. T.; Xia, Y. Nano Lett. 2006, 6, 1297.Google Scholar
  64. 64.
    (a) The HRTEM image of V2 O5 nanorods on TiO2 nanofibers is reproduced with permission from Reference [54d]. (b) The HRTEM image of GaP-GaAs nanowires is reproduced with permission from reference 54b. (c) The HRTEM image of multiwall carbon nanotubes is reproduced with permission from (copyright 2004 American Chemical Society): Lee, D. C.; Mikulec, F. V.; Korgel, B. A. J. Am. Chem. Soc. 2004, 126, 4951.Google Scholar
  65. 65.
    For extensive reviews of molecular electronics see: (a) Tour, J. M. Molecular Electronics: Com mercial Insights, Chemistry, Devices, Architecture and Programming; World Scientific: River Edge, NJ, 2003. (b) Tour, J. M.; James, D. K. in Handbook of Nanoscience, Engineering and Technology; Goddard, W. A., III; Brenner, D. W.; Lyshevski, S. E.; Iafrate, G. J. eds.,;RC: New York, 2003; pp. 4.1-4.28. (c) Tour, J. M. Acc. Chem. Res. 2000, 33, 791.Google Scholar
  66. 66.
    Field emission results from the tunneling of electrons from a metal tip into a vacuum, under an applied strong electric field (Chapter 7 will have more details on this phenomenon, and how it is exploited for high-resolution electron microscopy).Google Scholar
  67. 67.
    (a) Avouris, P. Acc. Chem. Res. 2002, 35, 1026. (b) Wind, S. J.; Appenzeller, J.; Martel, R.; Derycke, V.; Avouris, P. Appl Phys. Lett. 2002, 80, 3817. A recent strategy for the bottom-up design of CNT interconnects: Li, J.; Ye, Q.; Cassel, A.; Ng, H. T.; Stevens, R.; Han, J.; Meyyappan, M. Appl. Phys. Lett. 2003, 82, 2491.Google Scholar
  68. 68.
    Yakabson, B. I. Appl. Phys. Lett. 1998, 72, 918.CrossRefGoogle Scholar
  69. 69.
    Micro-Raman spectroscopy has shown that during tension, only the outer layers of MWNTs are loaded, whereas during compression, the load is transferred to all layers.Google Scholar
  70. 70.
    Salvetat, J.-P.; Briggs, G. A. D.; Bonard, J.-M.; Basca, R. R.; Kulik, A. J.; St öckli, T.; Burnham, N. A.; Forr ó , L. Phys. Rev. Lett. 1999, 82, 944.CrossRefGoogle Scholar
  71. 71.
    For a recent review, see: CNT stabilized polymers.Google Scholar
  72. 72. strength. For a very nice summary of specific stiffness/specific strength regions for various materials classes see: charts/spec-spec/basic.html
  73. 73.
    Sun, J.; Gao, L.; Li, W. Chem. Mater. 2002, 14, 5169.CrossRefGoogle Scholar
  74. 74.
    For a nice review regarding defect sites in CNTs, see Charlier, J.-C. Acc. Chem. Res. 2002, 35, 1063.Google Scholar
  75. 75.
    For a thorough recent review of the surface chemistry (noncovalent and covalent) of CNTs, see Tasis, D.; Tagmatarchis, N.; Bianco, A.; Prato, M. Chem. Rev. 2006, 106, 1105.Google Scholar
  76. 76.
    A interesting recent precedent related to the reversibly tunable exfoliation of SWNTs using poly(acrylic acid) at varying pH levels is reported by Grunlan, J. C.; Liu, L.; Kim, Y. S. Nano Lett. 2006,6,911.Google Scholar
  77. 77.
    Knupfer, M.; Reibold, M.; Bauer, H.-D.; Dunsch, L.; Golden, M. S.; Haddon, R. C.; Scuseria, G. E.; Smalley, R. E. Chem. Phys. Lett. 1997, 272, 38.CrossRefGoogle Scholar
  78. 78.
    Smalley, R. E. Discovering the Fullerenes, Nobel Lecture, 1996. May be found online at: (along with the Nobel lectures from Curl and Kroto).
  79. 79.
    It should be noted that the National Institute of Standards and Technology (NIST) has been recently focused on the development of standard synthesis, purification, and characterization techniques for CNTs. To date, there are a number of competing methods for SWNTs/MWNTs - all citing percent purity values that appear rather arbitrary. Indeed, purchasing a “90% pure SWNT” sample from multiple vendors will result in very different products! In order to continue the rapid progress in CNT synthesis/applications, it is essential that we set up a “gold standard” for CNTs that will immediately tell us what a certain purity level means. That is, if a “60% purity” value is cited, clarifying what the remaining 40% consists of (amorphous carbon, remaining catalytic metal, other nanotube diameters/morphologies, etc.)Google Scholar
  80. 80.
    Dai, H. Acc. Chem. Res. 2002, 35, 1035.CrossRefGoogle Scholar
  81. 81.
    Rao, C. N. R.; Govindaraj, A. Acc. Chem. Res. 2002, 35, 998, and references therein. For recent information regarding the role of alumina on the yield/morphology of supported CNT catalysts, see: Jodin, L.; Dupuis, A.-C.; Rouviere, E.; Reiss, P. J. Phys. Chem. B 2006, 110, 7328. It should be noted that the supported nanoclusters may reside within nanochannels to facilitate 1D growth, examples of these methods, which include both template and “closed space sublimation” (CSS) are (and references therein): (a) Li, J.; Papadopoulos, C.; Xu, J. M.; Moskovits, M. Appl. Phys. Lett. 1999,75,367. (b) Kyotani, T.; Tsai, L. F.; Tomita, A. Chem. Mater. 1996, 8, 2109. (c) Hu, Z. D.; Hu, Y. F.; Chen, Q.; Duan, X. F.; Peng, L.-M. J. Phys. Chem. B 2006, 110, 8263Google Scholar
  82. 82.
    Choi, H. C.; Kim, W.; Wang, D.; Dai, H. J. Phys. Chem. B 2002, 106, 12361. The first precedent for SWNT growth from gold nanoclusters has been recently reported: Bhaviripudi, S.; Mile, E.; Steiner, S. A.; Zare, A. T.; Dresselhaus, M. S.; Belcher, A. M.; Kong, J. J. Am. Chem. Soc. 2007, 129,1516.Google Scholar
  83. 83.
    The first precedent for (n ,m ) control of SWNT growth is: Lolli, G.; Zhang, L.; Balzano, L.; Sakulchaicharoen, N.; Tan, Y.; Resasco, D. E. J. Phys. Chem. B 2006, 110, 2108.Google Scholar
  84. 84.
    Resasco, D. E.; Alvarez, W. E.; Pompeo, F.; Balzano, L.; Herrera, J. E.; Kitiyanan, B.; Borgna, A. J. Nanopart. Res. 2002, 4, 131.CrossRefGoogle Scholar
  85. 85.
    Nikolaev, P.; Bronikowski, M. J.; Bradley, R. K.; Rohmund, F.; Colbert, D. T.; Smith, K. A.; Smalley, R. E. Chem. Phys. Lett. 1999, 313, 91. It should be noted that Fe(CO)5 is not the only system in which the precursor acts as the metal catalyst and carbon source. A number of metallocenes (e.g., ferrocene, cobaltocene, and nickelocene) have also been used; however, they typically result in MWNT growth rather than SWNTs. This is most likely due to the larger number of carbon atoms from cyclopentadienyl groups that must self-assemble, relative to smaller carbon precursors (e.g., CH4 , C2 H2 , etc.) used for SWNT growth.Google Scholar
  86. 86.
    Wagner, R. S.; Ellis, W. C. Appl. Phys. Lett. 1964, 4, 89. For a recent review of the solid-liquid-solid (SLS) and supercritical fluid-liquid-solid (SFLS) mechanisms for semiconductor nanowire growth, see: Wang, F.; Dong, A.; Sun, J.; Tang, R.; Yu, H.; Buhro, W. E. Inorg. Chem. 2006, 45, 7511. A recent precedent for the epitaxial growth of ZnO nanowires at the junction of nanowalls: Ng, H. T.; Li, J.; Smith, M. K.; Nguyen, P.; Cassell, A.; Han, J.; Meyyappan, M. Science 2003, 300, 1249.Google Scholar
  87. 87.
    The word “generally” is used, since there are also reports of nanowire growth at temperatures below the eutectic. For example, see: Adhikari, H.; Marshall, A. F.; Chidsey, E. D.; McIntyre, P. C. Nano Lett. 2006, 6, 318.Google Scholar
  88. 88.
    Cantoro, M.; Hofmann, S.; Pisana, S.; Scardaci, V.; Parvez, A.; Ducati, C.; Ferrari, A. C.; Blackburn, A. M.; Wang, K.-Y.; Robertson, J. Nano Lett. 2006, 6, 1107.CrossRefGoogle Scholar
  89. 89.
    Deng, W.-Q.; Xu, X.; Goddard, W. A. Nano Lett. 2004, 4, 2331.CrossRefGoogle Scholar
  90. 90.
    Graphite-encapsulated metal nanostructures are of increasing importance for magnetic applications such as high-density magnetic recording media; for example, see: Flahaut, E.; Agnoli, F.; Sloan, J.; O’Connor, C.; Green, M. L. H. Chem. Mater. 2002, 14, 2553, and references therein. Encap- sulation dominates over CNT growth at low temperatures since the kinetic energy is not sufficient for graphitic islands to lift off the catalyst surface. Hence, encapsulation may easily be limited, which enhances CNT growth, by maintaining elevated temperatures. Experimental results also show that small catalyst nanoclusters (diameters <2 nm) are free of graphite encapsulation since they do not contain a sufficient number of dissolved C atoms. However, for metal nanostructures >3 nm in diameter, calculations suggest that graphite encapsulation is thermodynamically preferred over SWNT growth. This is confirmed by the empirical observation that SWNTs form only on catalyst particles with diameters <2 nm.Google Scholar
  91. 91.
    Lee, Y. H.; Kim, S. G.; Jund, P.; Tomanek, D. Phys. Rev. Lett. 1997, 78, 2393.CrossRefGoogle Scholar
  92. 92.
    Hata, K.; Futaba, D. N.; Mizuno, K.; Namai, T.; Yumura, M.; Iijima, S. Science 2004, 306, 1362.CrossRefGoogle Scholar
  93. 93.
    Rummeli, M. H.; Borowiak-Palen, E.; Gemming, T.; Pichler, T.; Knupfer, M.; Kalbac, M.; Dunsch, L.; Jost, O.; Silva, S. R. P.; Pompe, W.; Buchner, B. Nano Lett. 2005, 5, 1209.CrossRefGoogle Scholar
  94. 94.
    For a recent review of inorganic-based nanotubes, see: Goldberger, J.; Fan, R.; Yang, P. Acc. Chem. Res. 2006, 39, 239, and references therein.Google Scholar
  95. 95.
    The top VLS mechanism was predicted using molecular dynamics calculations. The image was reproduced with permission from Ding, F.; Bolton, K.; Rosen, A. J. Phys. Chem. B 2004, 108, 17369. The middle VLS mechanism shows both “root growth” (c-d) and “folded growth” (e-g). The image was reproduced with permission from Lee, D. C.; Mikulec, F. V.; Korgel, B. A. J. Am. Chem. Soc. 2004,126,4951. The bottom mechanism, predicted by quantum mechanics/molecular mechanics, is one of the rare examples of an atomic-level picture of CNT growth. The image was reproduced with permission from Deng, W.-Q.; Xu, X.; Goddard, W. A. Nano Lett. 2004, 4, 2331.Google Scholar
  96. 96. - a recent press release indicates that EUV lithography will likely be implemented for high volume production by 2009, with feature sizes well below 32 nm.
  97. 97.
    In order to reduce the adhesion between a polymeric mold and a silicon/quartz master, the master surface is typically modified with a fluorosilane (e.g., CF3 (CF2 )6 (CH2 )2 SiCl3(g) ). In addition, the final removal of the mold may also be carried out in the presence of a liquid with a low viscosity such as methanol (solvent-assisted micromolding (SAMIM)).Google Scholar
  98. 98.
    A recent thorough review of nanofabrication using both hard and soft molds, as well as other forms of soft lithography, see: Gates, B. D.; Xu, Q.; Stewart, M.; Ryan, D.; Willson, C. G.; Whitesides, G. M. Chem. Rev. 2005, 105, 1171.Google Scholar
  99. 99.
    For example, see: Chou, S. Y.; Krauss, P. R.; Renstrom, P. J. Science 1996, 272, 85.Google Scholar
  100. 100.
    For example, see: Jackman, R. J.; Wilbur, J. L.; Whitesides, G. M. Science 1995, 269, 664.Google Scholar
  101. 101.
    Im, J.; Kang, J.; Lee, M.; Kim, B.; Hong, S. J. Phys. Chem. B 2006, 110, 12839.CrossRefGoogle Scholar
  102. 102.
    Myung, S.; Lee, M.; Kim, G. T.; Ha, J. S.; Hong, S. Adv. Mater. 2005, 17, 2361.CrossRefGoogle Scholar
  103. 103.
    (a) Odom, T. W.; Thalladi, V. R.; Love, J. C.; Whitesides, G. M. J. Am. Chem. Soc. 2002, 124, 12112. (b) Odom, T. W.; Love, J. C.; Wolfe, D. B.; Paul, K. E.; Whitesides, G. M. Langmuir 2002, 18, 5314.Google Scholar

Copyright information

© Springer 2007

Authors and Affiliations

  • Bradley D. Fahlman
    • 1
  1. 1.Central Michigan UniversityMount PleasantUSA

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