Monitoring mechanical motion of carbon nanotube based nanomotor by optical absorption spectrum

The optical absorption spectra of nanomotors made from double-wall carbon nanotubes have been calculated with the time-dependent density functional based tight binding response method. When the outer short tube of the nanomotor moves along or rotates around the inner long tube, the peaks in the spectra will gradually evolve and may shift periodically, the amplitude of which can be as large as hundreds of meV. We show that the features and behaviors of the optical absorption spectra could be used to monitor the mechanical motions of the double-wall carbon nanotube based nanomotor.