US Patent 7659139 - Selective CNT destruction by irradiation

http://www.freepatentsonline.com/7659139.html

The fabrication of single walled carbon nanotubes usually results in a mixture of about 1/3 metallic nanotubes and 2/3 semiconducting nanotubes. Several methods exist to sort the metallic from the semiconducting nanotubes such as using ac dielectrophoresis, DNA chromatography, and destruction of metallic nanotubes by electric current. This patent from Sony includes some basic claims for an another method of selective destruction of the metallic or semiconductor nanotubes using laser irradiation. Claims 5 and 9 read:

5. A method for destroying metallic carbon nanotubes comprising irradiating metallic carbon nanotubes with energy beams, wherein the energy beams are laser light.

9. A method for destroying semiconducting carbon nanotubes, the method comprising irradiating with energy beams for destruction of semiconducting carbon nanotubes.