Raman spectroscopic investigation of carbon nanowalls

Two-dimensional carbon nanowalls (CNWs) were prepared by microwave plasma-enhanced chemical-vapor deposition and scanning electron microscopy was used to observe their morphologies. The Raman observations of different sample orientations and polarizations show that CNWs are well crystallized. Micro-Raman scattering measurements were also carried out with different excitation laser lines (325, 488, 514, 532, and 633 nm). The D band shows a very strong shift of 46.19 cm(-1)/eV with excitation laser energy and this has been explained by the double resonance effect. The decreasing intensity ratios I-D/I-G and I-D(')/I-G with increasing laser excitation energy were detected and discussed. (c) 2006 American Institute of Physics.