Chirality selection of single-walled carbon nanotubes by laser resonance chirality selection method

We propose a laser resonance chirality selection method to select single-walled carbon nanotubes (SWNTs) with specific chirality from mass of SWNTs by intense laser irradiation. This technique exploits the multiple Van Hove singularities in the density of states of SWNTs expected for one-dimensional confinement. Absorption of the exciting laser beam can be strongly enhanced for SWNTs with specific chirality when the energy of the incident photon matches the energy of the allowed electronic transitions. As a result of the resonance effect, when the excitation power density of the laser beam increases in an atmosphere of air, at a certain threshold excitation power density, only these SWNTs are oxidized and are removed selectively. With Raman scattering measurements, we have demonstrated that SWNTs with specific chirality are selectively removed after intense laser irradiation. (C) 2004 American Institute of Physics.