Formation of long-lived image states around carbon nanotubes

Patrick Richard, Mikhail Zamkov, Zenghu Chang, Bing Shan
Kansas State University, Manhattan, Kansas 66503

The long-lived electronic states with wave functions enclosing a carbon nanotube (NT) were observed in two-color time-resolved photoemission experiments[1]. These cylindrical "electronic rings" constitute a new class of surface image states due to their quantized angular motion[2,3]. The electron rotation about the axis of the nanotube gives rise to a centrifugal force that virtually detaches the electron charge-cloud from the tube's body. This isolation results in enhanced lifetimes that were measured to be one order of magnitude longer than those of image states forming above metal surfaces. The experiments were performed using the high-purity (> 95%) samples of individual multi walled NTs. The current efforts are aimed towards the observation of these "exotic" states around the isolated double walled NTs as well as in bundles of single walled NTs.

References:

1) M. Zamkov, N.Woody, S. Bing, H. S. Chakraborty, Z. Chang, U. Thumm, and P. Richard; "Time-Resolved Photoimaging of Image-Potential States in Carbon Nanotubes"; Phys. Rev. Lett. 93, 156803 (2004).
2) B. E. Granger, P. Kral, H. R. Sadeghpour, and M. Shapiro; "Highly Extended Image States around Nanotubes"; Phys. Rev. Lett. 89, 135506 (2002).
3) M. Zamkov, H. S. Chakraborty, A. Habib, N. Woody, U. Thumm, and P. Richard; "Image-potential states of single- and multiwalled carbon nanotubes"; Phys. Rev. B 70, 115419 (2004).

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Submitted to WONTON, July 2005 in Telluride, CO.

 

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