Raman spectroscopy of PbI_2-filled double-walled carbon nanotubes

摘要

PbI_2-filled double-walled carbon nanotubes (PbI_2@DWCNTs) have been studied by Raman spectroscopy employing a 785 nm excitation wavelength and their spectra have been compared to those of pristine double-walled carbon nanotubes (DWCNTs). The DWCNTs were synthesized by catalytic chemical-vapor deposition. Assignment of the radial breathing modes and the tangential modes was done based on the one-dimensional electronic energy-band structure of carbon nanotubes. It was established that PbI_2@DWCNTs can be unambiguously identified by the position of the second-order G' band and its rate of downshift due to power-density increase of the excitation radiation. After laser-assisted disintegration of the PbI_2@ DWCNTs the PbI_2 band has been detected and compared to those of the powder PbI_2. The one-dimensional PbI_2 crystal chains show downshifted Raman bands as compared to those of the powder material.