High temperature Raman spectroscopy studies of carbon nanowalls

High temperature Raman experiments were carried out on carbon nanowalls (CNWs). The intensity of the defect‐induced D mode decreased significantly after the sample was heated in air ambient. The Raman intensity ratio of D mode and G mode, I_D/I_G, changed from 2.3 at room temperature to 1.95 after the sample was heated to 600 °C. This change was attributed to the removal of surface amorphous carbon by oxidation. In contrast to I_D/I_G, the intensity ratio of the D′ mode and the G mode, I_D′/I_G, did not change much after heating, indicating that the surface amorphous carbon and surface impurity do not contribute as much to the intensity of the D′ mode. The dominant contributor to the D′ mode could be the intrinsic defects. Copyright © 2007 John Wiley & Sons, Ltd.