Quantum electronic orbits discovered around carbon nanotubes

Electrons orbiting a nanotube
Formation of tubular electronic states around carbon nanotubes is demonstrated in recent experiments by M. Zamkov and collaborators.
Using two-color photoelectron emission researches can populate and subsequently observe the special group of electronic states with wave functions enclosing a carbon nanotube. These cylindrical “electronic tubes” constitute a new class of “image” states due to their quantized angular motion. 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. By experiencing the lattice structure parallel to the tube's axis these rings can act as powerful scanning probes of nanotube electronic properties. The first images shows such electronic orbits schematically. The lower images gives a calculated shape of the radial part of the electronic wave function. This work represent the first experimental evidence for the existence of stable image-potential states orbiting carbon nanotubes. The measured lifetimes are found to be significantly longer compared to n = 1 image state on graphite. This facts indicates a qualitative difference in electron decay dynamics between carbon nanotubes and planar graphene layers. Electrons orbiting nanotubes can be used in novel computing and memory devices and possibly qubits. Reference: M. Zamkov, N. Woody, B. Shan, H. S. Chakraborty, Z. Chang, U. Thumm, and P. Richard James R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, USA Phys. Rev. Lett. 93, 156803 (2004)
See also images:
Visualization of the radial part of the electron wave function. The quantum numbers are n = 3; l =1. The diameter of the nanotube is 5 nm.
Visualization of the radial part of the electron wave function. The quantum numbers are n = 3; l =1. The diameter of the nanotube is 5 nm.
The cylindrical superstructures are composed of silver nanoparticles with V-shaped amphiphilic arms. The short rod-like and spherical assemblies are made of gold nanoparticles with the same V-shaped amphiphilic arms.  The self-assembly occurs upon slow addition of water to solution of nanoparticles in organic solvent called tetrahydrofuran. The resulting mixture is then dialyzed against pure water in order to remove organic solvent and obtain a pure aqueous solution of the superstructures (they remain in water without any precipitation, just like micelles).
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