18 research outputs found
A Mechanism for Cutting Carbon Nanotubes with a Scanning Tunneling Microscope
We discuss the local cutting of single-walled carbon nanotubes by a voltage
pulse to the tip of a scanning tunneling microscope. The tip voltage (~3.8 eV) is the key physical quantity in the cutting process. After
reviewing several possible physical mechanisms we conclude that the cutting
process relies on the weakening of the carbon-carbon bonds through a
combination of localized particle-hole excitations induced by inelastically
tunneling electrons and elastic deformation due to the electric field between
tip and sample. The carbon network releases part of the induced mechanical
stress by forming topological defects that act as nucleation centers for the
formation of dislocations that dynamically propagate towards bond-breaking.Comment: 7 pages, 6 postscript figures, submitted to PR
Imaging Electron Wave Functions of Quantized Energy Levels in Carbon Nanotubes
Carbon nanotubes provide a unique system to study one-dimensional
quantization phenomena. Scanning tunneling microscopy is used to observe the
electronic wave functions that correspond to quantized energy levels in short
metallic carbon nanotubes. Discrete electron waves are apparent from periodic
oscillations in the differential conductance as a function of the position
along the tube axis, with a period that differs from that of the atomic
lattice. Wave functions can be observed for several electron states at adjacent
discrete energies. The measured wavelengths are in good agreement with the
calculated Fermi wavelength for armchair nanotubes.Comment: 11 pages, 4 figures in seperate PDF fil