2. Steve Cronin University of Southern California Electrical Engineering - Electrophysics Optical and Electronic Measurements of Individual Carbon Nanotubes

3. Imagine rolling a sheet of graphite into a seamless cylindrical tube Honeycomb Graphite Sheet Two integers (n,m) determine all the properties of a carbon nanotube. Nanotubes can have metallic or semiconducting electronic structure, if (n-m)/3. What is a Carbon Nanotube? Chirality (n,m): C h = 4a 1 + 2a 2 = (4,2)

4. AFM of Carbon Nanotube and DNA Molecules Bockrath, et al., Nano Lett., 2, 187 (2002). Carbon Nanotube DNA

5. Why Study Carbon Nanotubes? 1nm in diameter, up to 1cm in length, aspect ratio of 10 7 1 defect in 10 12 C atoms => ballistic conduction High melting point ~3800 o C High young’s modulus 1TPa (10 3 times diamond) High electronic current carrying capacity (10 9 A/cm 2 ) ~10 3 times higher than that of the noble metals Thermal conductivity 6600W/mK at room temperature is twice the maximum known bulk thermal conductor, isotropically pure diamond = 3320W/mK Despite 18,000 publications, no large scale commercial applications of nanotubes Li, Yu, Rutherglen, Burke, Nano Lett., 4 2003 (2004) Fan, Goldsmith, Collins, Nature Materials, 4, 906 (2005)

6. V gate Gate NT V bias SiO 2 doped silicon onoff 1m1m Nanotube Field Effect Transistor (NT-FET) metallic semiconducting

7. Single Nanotube Raman Spectroscopy Despite the extremely small geometric cross-section the Raman signal from a single isolated nanotube can be observed. E ii 10 5 enhancement in scattering cross-section due to singularities in the DOS Resonance occurs when E laser =E ii Only observe nanotubes that are resonant with E laser Semiconducting Metallic RBMG-band Jorio, et al., PRL, 86, 1118 (2001)

8. Strain Nanotubes AFM tip 1m1m unstrained length =3.8  m strain = 20nm  0.53%  5.3GPa Stress

9. Raman Spectra of Strained NT unstrained length =3.8  m strain = 20nm  0.53%  5.3GPa Stress AFM tip 1m1m Cronin, et al., PRL, 93, 167401 (2004). D, G, G’ bands are downshifted by 16.1, 14.8 and 27.7cm -1 (5 times bulk) Lower phonon frequencies as C-C bond length increases

10. broken Raman Spectra of Broken NT D, G and G’ downshift by 27, 14 and 40cm -1 Broken tube resumes original D, G and G’ values. Strain deformations are elastic Cronin, et al., PRL, 93, 167401 (2004). strain=1.65%

11. AFM tip 1m1m 1m1m 2m2m Thank You!

12. AFM tip 1m1m 1m1m 2m2m Thank You! Rajay Kumar, Hao Zhou, Adam Bushmaker (USC) A. Stolyarov, Prof. M. Tinkham (Harvard) R. Barnett, E. Demler (Harvard) Y. Yin, A. Walsh, Prof. A.K. Swan, Prof. B.B. Goldberg (BU) Prof. M.S. Dresselhaus (MIT) People: NIRT ECS-0210752 NSF Grant Nos. DMR-01-16042 and DMR-02-44441 NSEC Grant No. PHY-01-17795 Dupont-MIT alliance Grants: