Low-Frequency and Abnormal Raman Spectrum in SnO2 Nanorods
LIU Ying-Kai1,2,3, DONG Yi2, WANG Guang-Hou2
1Department of Physics, Yunnan Normal University, Kunming 650092
2National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093
3Department of Physics and Materials Science, Center of Super-Diamond and Advanced Films (COSDAF), 83 Tat Chee Avenue, Kowloon, Hong Kong
Low-Frequency and Abnormal Raman Spectrum in SnO2 Nanorods
LIU Ying-Kai1,2,3;DONG Yi2;WANG Guang-Hou2
1Department of Physics, Yunnan Normal University, Kunming 650092
2National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093
3Department of Physics and Materials Science, Center of Super-Diamond and Advanced Films (COSDAF), 83 Tat Chee Avenue, Kowloon, Hong Kong
Abstract： Raman-scattering spectra in SnO2 nanorods with different diameters were obtained at room temperature and the low-frequency Raman peaks have been observed for the first time. It was found that the low-frequency peaks shifted to high frequencies as the nanorod diameter decreased. The size dependence of the low-frequency peaks in SnO2 nanorods can be identified by the surface modes among the confined acoustic modes of SnO2 nanorods, given by solving Lamb theory. In addition, the Raman peaks of SnO2 nanorods not only vary with the excitation wavelength (514.5 nm and 785 nm), but have their line-width broadening and the line shapes asymmetric as well. Moreover, some IR active modes became Raman-active induced by disorders such as local lattice imperfections and oxygen deficiencies in the thinner nanorods when the diameter of the nanorod decreased down to 15 nm or smaller.
2004, Vol. 21 
