Structural Analysis of Encapsulated Single-Walled Carbon Nanotubes

Abstract

Tip-enhanced Raman spectroscopy revealed the nanoscale chemical properties of organic molecules encapsulated in single walled carbon nanotubes (SWNTs). Our approach is based on an enhanced electric field near a laserirradiated metal tip functioning as a Raman excitation source. The enhanced field can successfully act on encapsulated molecules through the walls of the SWNTs to extract molecular vibrational information -carotene, which exhibits several active Raman modes under visible light illumination, was used as the encapsulated molecule. Tip-enhanced Raman spectra measured at seven different positions on SWNT bundles showed that - carotene molecules inside the tubes were not uniformly distributed. It is also found that the filling rate and peak position of the radial breathing mode of the SWNTs are linearly correlated.