Molecular photoeffect in single- and multi-wall carbon nanotubes with physisorbed oxygen molecules

The EPR spectra of high purity single-walled and multi-walled semiconducting carbon nanotubes exhibit wide resonance lines (154 ± 5 mT and 159 ± 5 mT, respectively, at room temperature). The broadening of EPR lines is due to magnetic dipole-dipole interaction with the spin-triplet ground state oxygen molecules physisorbed on the carbon nanotubes surface. Here we show that the emission of O2 molecules occurs under the photons with energy of 2.33 eV that leads to narrowing of the EPR line. The number of molecules emitted from nanotubes is proportional to the flux of incident radiation, in full analogy with the first law of the classical photoelectric effect.