纳米碳管模板法制取的GaP纳米棒拉曼光谱研究

STUDY ON THE RAMAN SPECTRA OF GaP NANORODS SYNTHESIZED WITHIN CARBON NANOTUBE TEMPLATES

报道了用纳米碳管模板法制备的GaP纳米棒的拉曼光谱特征 .观测到声子限制效应引起的GaP纳米棒TO和LO模的红移 .红移量一般在 2～ 10cm-1之间 ,与所测到的纳米棒的尺寸有关 .在偏振特性研究中 ,发现GaP纳米棒的偏振特性不能用单根纳米棒的选择定则来解释 ,而与测量光斑内多根纳米棒的无序取向有关 .无序程度越高 ,偏振特性的方向性越弱 .当激发光功率增加时 ,GaP纳米棒的TO和LO模的频率显著减少 ,表明纳米棒中的激光加热效应比体材料中强很多 .而且GaP纳米棒的拉曼散射强度随激发光功率的增加先饱和 ,然后减小 ,表明在强激发功率下GaP纳米棒中的缺陷会迅速增加 .

The Raman spectra of GaP nanorods grown in carbon nanotube templates have been reported. The red shifts of the TO and LO modes were observed due to phonon confinement effect in GaP nanorods. The measured red shifts range from 2 to 10cm(-1) depending on the size of the measured nanorods. It has been found that the polarization properties, which cannot be well explained by the selection rules of single nanorod, result from the direction disorder of nanorods in the measured area. The more the disorder is, the weaker the directionality of polarization properties is. The decrease of the Raman frequency of the TO and LO mode of the nanorods with the increasing power of the exciting laser suggests that the heating effect of the nanorods is far stronger than the bulk material. In addition, the saturation and then decrease of the Raman intensity with the increasing laser power indicate the rapid increase of the defects in the nanorods exposed to a strong exciting laser.