Presented by: Jonathan Claussen 18 February 2009

1. Translational and Rotational Dynamics of Individual Single-Walled Carbon Nanotubes in Aqueous Suspension Presented by: Jonathan Claussen 18 February 2009

2. Optical Properties of SWCNTs SWCNTs - semi-conducting SWCNT act as near-infrared (NIR) fluorophores - high photostability - absence of emission intermittency - strong optical anistropy - resistance to photobleaching - optical anisotropy (absorption and (emission transitions are strongly polarized along the tube axis). Notes from Wiki (http://en.wikipedia.org/wiki/) Flourophores - It is a functional group in a molecule which will absorb energy of a specific wavelength and re-emit energy at a different (but equally specific) wavelength. Photobleaching is the photochemical destruction of a fluorophore typically caused by overexposing the fluorphores. Fluorescence intermittency – fluorescence “blinking” Emission of SWCNT 15 – 20 meV (950 < λ < 1600) nm

3. Translational Diffusion of SWCNTs Einstein Equations (Kinetic Theory) DT = kBTbT DT =Translational Diffusion Coefficients kB = Boltzman constant T = sample temperature (296K) bT = translational mobility Diameter of CNTs ≈ 5 +/- 2nm uncertainty only ≈ 12% in Dtrans for 200 nm long SWCNTs http://en.wikipedia.org/wiki/Einstein_relation_(kinetic_theory) For Derivation See η = solution viscosity (1.0 mPa • s) L = length of cylinder = end-correction coefficients = end-correction coefficients

4. Rotational Diffusion of SWCNTs Einstein Equations (Kinetic Theory) DR = kBTbR DR =Translational Diffusion Coefficients kB = Boltzman constant T = sample temperature (296K) bR = rotational mobility http://en.wikipedia.org/wiki/Einstein_relation_(kinetic_theory) For Derivation See kB = Boltzman constant T = sample temperature (296K) η = solution viscosity (1.0 mPa • s) = length-dependent end-correction coefficients S. Broersma, J. Chem. Phys., 74, 6989-6990 (1981)

5. End-correction coefficients Tobacco Mosaic Virus S. Broersma, J. Chem. Phys., 74, 6989-6990 (1981) b = cylinder half width a = cylinder half length 2b 2a Length = 300 nm Width = 10 nm http://en.wikipedia.org/wiki/Tobacco_mosaic_virus

6. Optical Anisotropy Video micrographs Emission Intensity vs. excitation polarization angle Emission intensity vs. emission energy

7. Diffuse Movement of SWCNTs in Solution Experiment 44 SWCNTs in 2μm thick cell Excited with linearly polarized light Nanotube lengths ≈ 130 – 6000nm Videomicrographs of CNTs in solution numerically analyzed by a standard mean-squared displacement (MSD) method Linearity of graphs indicate SWCNTs are moving diffusively.

8. SWCNT Emission Signal vs. Rotational Speed Showing relation between SWCNT emission signal and SWCNT rotational Stationary SWCNTs A: Short SWCNT exposed for 10 ms B: Long SWCNT exposed for 1 ms Water/glycerin fluid

9. Chirality/Emission Intensity Chirality of the SWCNTs can be obtained by analyzing the emission intensity.

10. Numerical Model SWCNT length = 100nm - 10μm Numerical Modeling based upon “Random Walk Theory” Random Walks in Biology HC Berg - 1993 - rieke-server.physiol.washington.edu Variability increases as Dtrans increases because long SWCNTs experience thermally induced bending and wall drag effect. Model 1: idealized SWCNT rotational diffusion model based on above data Model 2: adjust for non-ideal absortion anisotropy (raised I/Imax from 0.290 to 0.315) Model 3: adjust for constrained rotation of longer nanotubes Model 4: adjusts for wall drag effects (increased slightly the effective viscosities)