Interaction of Laser Light and Electrons with Nanotubes
H.R. Sadeghpour, B.E. Granger and P. Král
Harvard University, US
Keywords: carbon nanotubes, nanomotors, image states, dots
Technological leaps of the last two decades have opened windows of opportunity for designing and controlling electronic states in novel systems. The fabrication of quantum dots in semiconductor devices has led to the invention of single-electron transistors. and controllable single photon emitters. Such designer atoms are ideal settings for the control and manipulation of electronic states. Carbon nanotubes (CNT), first synthesized in 1991 by Iijima as graphitic carbon needles, have remarkable electrical and mechanical properties. Carbon nanotubes are ideal for investigation at the interface of atomic and nanoscopic physics. Our aim has been to bring atomic physics techniques to the study of interaction of light and particles with nanotubes. In one such application, we calcualted the absorption of circularly-polarized infrared photons by the optically-active resonant phonon modes in CNT. We found that through the transfer of photon angular momentum to the phonon modes and their eventuall decay into two acoustical phonons, CNTs would rotate with a frequency of 28 GHz. This proof-of-concept study demonstrated that nanotubes with their particular mechanical and electrical properties could form parts of nanoscopic motors, centrifuges or stabilizers. In a recent work, we showed that conducting CNTs do indeed have Rydberg-like excitations. However, because an electron can have angular momentum about the nanotube axis, a centrifugal barrier forms, dramatically increasing the lifetimes of the states compared to their counterparts above flat surfaces. Recent experimental realization of suspended CNT network provides the necessary ground for observing the proposed states.
Nanotech 2004 Conference Technical Program Abstract