二维材料的拉曼光谱学研究
详细信息 查看官网全文
- 英文论文题名：Unifiedly understanding the Raman spectroscopy in two-dimensional materials
- 论文作者：谭平恒
- 英文论文作者：Ping-Heng Tan ; SKLSM ; Institute of Semiconductors
- 年：2016
- 作者机构：中国科学院半导体研究所半导体超晶格国家重点实验室;
- 论文关键词：二维材料 ; 范德华层间相互作用 ; 达维多夫劈裂 ; 共振拉曼光谱
- 会议召开时间：2016-07-01
- 会议录名称：中国化学会第30届学术年会摘要集-第三十五分会：纳米表征与测量
- 语种：中文
- 分类号：TB303;O657.37
- 学会代码：ZGHY
- 会议名称：中国化学会第30届学术年会-第三十五分会 ; 纳米表征与测量
- 会议地点：中国辽宁大连
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：1
- 文件大小：210k
- 原文格式：D
- 会议级别：全国
摘要
范德华层间相互作用将使得层状材料的物理性质与其层数紧密相关[1],例如,每个单层材料声子模式将劈裂成N层材料的N个相应的振动模式。在层状材料中,层间相互作用可以直接由超低频剪切(S)和呼吸层(LB)模来探测。范德华层间相互作用远远弱于每一层内原子之间的共价键,因此相对于S和LB模,高频光学模式的峰位对层数不太敏感。因此,层间弱的范德华层间相互作用是如何影响高频声子的频率并不清楚。在这里,我们以多层MoTe2作为模板来探测弱的范德华层间相互作用如何影响多层二维材料的高频振动模频率[2]。在共振激发条件下,观察到ML-MoTe2中数目与层数相关的达维多夫劈裂模式,并基于对称性分析对所观察到的模式进行了进一步指认。达维多夫模式之间的劈裂值可以由相应的LB模式与无耦合的高频振动模间的耦合来理解。达维多夫劈裂模式的各种拉曼光谱研究表明,必须选择合适的激发才能观察到NL-MoTe2的达维多夫劈裂。本工作揭示了范德华斯相互作用如何影响高频振动模的频率,使得我们可以对过渡金属硫族化合物等二维材料的拉曼光谱进行统一的描述和理解。
How the interlayer interaction affects the frequency of the high frequency optical modes is not clear. Here, we treat multilayer MoTe2 as a template to probe the effect of van der Waals interlayer interactions on the high-frequency modes in multilayer flakes. Under the resonant excitation condition, we observe layer number dependent Davydov components in ML-MoTe2, which deriving from the Raman-active A1' mode of 1L-MoTe2 at ~172 cm-1. More than one Davydov components are observed in NL-MoTe2 for N>2 by Raman spectroscopy. The Davydov splitting between two components can be well understood by the coupling with the corresponding LB modes. The different resonant profiles for the two Davydov components in 3L-MoTe2 indicates that proper excitation energy must be chosen to observe the Davydov splitting in NL-MoTe2. Our work reveals how the van der Waals interactions affect the frequency of the high frequency intralayer phonon modes and expands the understanding on the lattice vibrations and interlayer coupling of transition metal dichalcogenides and other two-dimensional materials.
How the interlayer interaction affects the frequency of the high frequency optical modes is not clear. Here, we treat multilayer MoTe2 as a template to probe the effect of van der Waals interlayer interactions on the high-frequency modes in multilayer flakes. Under the resonant excitation condition, we observe layer number dependent Davydov components in ML-MoTe2, which deriving from the Raman-active A1' mode of 1L-MoTe2 at ~172 cm-1. More than one Davydov components are observed in NL-MoTe2 for N>2 by Raman spectroscopy. The Davydov splitting between two components can be well understood by the coupling with the corresponding LB modes. The different resonant profiles for the two Davydov components in 3L-MoTe2 indicates that proper excitation energy must be chosen to observe the Davydov splitting in NL-MoTe2. Our work reveals how the van der Waals interactions affect the frequency of the high frequency intralayer phonon modes and expands the understanding on the lattice vibrations and interlayer coupling of transition metal dichalcogenides and other two-dimensional materials.
引文
[1]Tan,P.H.;Han,W.P.;Zhao,W.J.;Wu,Z.H.Nature Materials 2012,11:294.
[2]Song,Q.J.;Tan,Q.H.;Zhang,X.;Wu,J.B.Phys.Rev.B,2016,93(11):115409.
[2]Song,Q.J.;Tan,Q.H.;Zhang,X.;Wu,J.B.Phys.Rev.B,2016,93(11):115409.