Kuok M H, Lim H S, Ng S C, Liu N N, Wang Z K
Department of Physics, National University of Singapore, Singapore 117542, Republic of Singapore.
Phys Rev Lett. 2003 Jun 27;90(25 Pt 1):255502. doi: 10.1103/PhysRevLett.90.255502. Epub 2003 Jun 24.
The vibrational modes in three-dimensional ordered arrays of unembedded SiO2 nanospheres have been studied by Brillouin light scattering. Multiple distinct Brillouin peaks are observed whose frequencies are found to be inversely proportional to the diameter (approximately 200-340 nm) of the nanospheres, in agreement with Lamb's theory. This is the first Brillouin observation of acoustic mode quantization in a nanoparticle arising from spatial confinement. The distinct spectral peaks measured afford an unambiguous assignment of seven surface and inner acoustic modes. Interestingly, the relative intensities and polarization dependence of the Brillouin spectrum do not agree with the predictions made for Raman scattering.
通过布里渊光散射研究了未嵌入的SiO₂纳米球三维有序阵列中的振动模式。观察到多个不同的布里渊峰，其频率与纳米球的直径（约200 - 340纳米）成反比，这与兰姆理论一致。这是首次在纳米颗粒中通过空间限制观察到声学模式量子化的布里渊现象。所测量的不同光谱峰明确地确定了七种表面和内部声学模式。有趣的是，布里渊光谱的相对强度和偏振依赖性与拉曼散射的预测不一致。
