Effect of water filling on the electronic and vibrational resonances of carbon nanotubes:: Characterizing tube opening by Raman spectroscopy

Water accessibility of single wall carbon nanotubes (SWCNTs) can be monitored by resonant Raman spectroscopy (RRS) (see figure and cover) of the radial breathing modes of bile salt-solubilized CNTs. The RRS features of empty and water-filled CNTs can be very well resolved, and vibrational and electronic shifts and broadenings have been accurately determined. The results also lead to a simple ratiometric method to quantify tube opening under various chemical and mechanical treatments.