Adsorption of oxygen molecules on individual single-wall carbon nanotubes

Our study of the adsorption of oxygen molecules on individual semiconductiong single-walled carbon nanotubes at ambient conditions reveals that the adsorption is physisorption, the resistance without O2 increases by approximately two orders of magnitude as compared to that with O2, and the sensitive response is due to the pinning of the Fermi level near the top of the valence band of the tube, resulting from impurity states of O2 appearing above the valence band.