Room Temperature Electron Spin Resonance of the Purified Carbon Nanotubes Produced in Different Helium Pressures

The electron spin resonance(ESR) of purified carbon nanotubes prepared under different helium pressures from 20.0 to 80.0kPa in arc discharge has been measured. The dependence of the ESR spin density, linewidth and g value of the purified nanotubes on the helium pressure is found. The electronic properties of purified nanotubes varying with He pressure are discussed.