双层石墨烯位于1800—2150cm^(-1)频率范围内的和频拉曼模

The second-order combination Raman modes of bilayer graphene in the range of 1800–2150 cm^(-1)

文章利用拉曼光谱研究了双层石墨烯在1800—2150 cm-1范围内的和频拉曼模.基于双共振拉曼散射理论,利用多波长激光拉曼散射结合声子色散曲线分别从实验上和理论上分析发现,双层石墨烯在此频率范围内主要存在4个拉曼模,它们主要由LO和LA或iTA按不同共振散射方式所组成的4个和频模,而iTO和oTO参与和频的可能性很小.文章澄清了学术界在1800—2150 cm-1频率范围内和频模的解释,有助于进一步深入理解多层石墨烯在此范围内的和频模.

In this paper, Raman modes of bi-layer graphene are investigated in detail in the frequency region between 1800 and2150 cm-1. There are four dominant Raman modes in this frequency region. The frequencies of these modes dependent on excitation energy are revealed from the measurement with multi-wavelength lasers, which can be fully understood based on double resonance Raman scattering and the phonon dispersion relation of monolayer graphene. The results show that these Raman modes can be assigned to the combinational modes from the fundamental modes of iTA, LA and LO phonons, but not from iTO and oTO phonons as reported in the previous works. This study benefits us toward the full understanding of lattice dynamics of monolayer and multilayer graphenes.