Characterization of MWCNT in Dry Powder Form. Characterization of multi-walled carbon nanotubes was determined using electron microscopy and Raman spectroscopy. (A & C) The diameter of the MWNCTs was determined by measuring individual nanotubes visualized by TEM. (B) This SEM image shows a bundle of MWCNTs, with individual nanotubes indicated by arrows. The length of individual nanotubes was determined to be several μm long using SEM. (D) The Raman spectrum of MWCNT obtained using 514.5 nm laser excitation. The presence of strong disorder band (ID/IG peak ratio) suggests the existence of structural defects as determined by Raman spectroscopy.