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酞菁铅在石墨烯表面吸附行为的拉曼光谱研究

ISSN号：1000-6818
期刊名称：物理化学学报
时间：0
页码：2355-2362
分类：O647[理学—物理化学;理学—化学]
作者机构：[1]北京大学化学与分子工程学院,北京大学纳米化学研究中心,北京100871
相关基金：国家自然科学基金（51121091 50972001 21129001）; 科技部项目（2011CB932601 2011YQ3012402）资助
相关项目：碳纳米管/石墨烯生长过程的原位拉曼光谱研究

作者：凌曦|张锦|

关键词：石墨烯, 酞菁铅, 石墨烯增强拉曼散射, 分子形变, Graphene, PbPc, Graphene enhanced Raman scattering, Molecular deformation

中文摘要：

利用石墨烯增强拉曼散射效应可以获得与石墨烯接触的某些分子的拉曼增强信号,并且对于不同的分子或振动模,其拉曼增强因子不同.根据这一特征,本工作利用拉曼光谱技术对石墨烯表面上酞菁铅（PbPc）分子Langmuir-Blodgett（LB）膜在退火过程中吸附构型的变化进行了跟踪研究.发现随着退火温度的升高,石墨烯表面上PbPc分子的拉曼信号经历了一个先增强后减弱的过程,在升华温度点附近强度达到最大,表明PbPc发生了由直立向平躺取向的转变;同时,在PbPc分子升华温度点附近,由于对称性破坏导致散射截面低的振动模出现,并且该振动模强度随着退火温度的进一步升高而增强,表明非平面的PbPc分子受石墨烯π-π相互作用的影响而形变加剧,向平面结构转变;在更高的退火温度下,则出现一些不属于PbPc分子的拉曼振动峰,表明PbPc分子在石墨烯表面由Pb（II）被还原成Pb（0）.

英文摘要：

Using graphene-enhanced Raman scattering,the Raman signals of molecules attached to graphene can be obtained.For different molecules and vibrational modes,the enhancement factors are different.Here,we have investigated the variation in the adsorption behavior of lead phthalocyanine （PbPc） Langmuir-Blodgett （LB） films on graphene under annealing using Raman spectroscopy.With increasing annealing temperature,it was found that the Raman intensity of the PbPc molecules first increased and then decreased.At the sublimation temperature,the enhanced Raman signal was the strongest,indicating that the orientation of the PbPc molecules had changed from perpendicular to parallel to the graphene surface.As the annealing temperature was increased towards the sublimation temperature,some vibrational modes with low Raman scattering cross-section appeared,and they were enhanced at higher temperatures.This indicates that the PbPc molecules are deformed due to π-π interactions with graphene,and change their structure from nonplanar to planar.When the annealing temperature was increased even further,some new vibrational modes appeared,which can be attributed to the reduction of Pb（II） to Pb（0） in the PbPc molecules.