ESR study of potassium-doped aligned carbon nanotubes

Opened, potassium-doped, and aligned carbon nanotubes were studied by electron spin resonance (ESR) measurements. Moderate K doping lowers the g factor of the pristine sample to 2.0028, and erases all the angular dependence. The Pauli susceptibility increases a factor of 3 upon doping, but the considerable Curie component shows that the tubes have suffered serious damage during the doping/depletion procedure. The temperature dependence of the ESR linewidth and g factor testifies that the K-doped tubes are still good conductors.