State Key Laboratory of Molecular Engineering of Polymers, Ministry of Education, Department of Macromolecular Science, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, People's Republic of China.
ACS Appl Mater Interfaces. 2013 Jun 12;5(11):5085-90. doi: 10.1021/am400938z. Epub 2013 May 14.
Graphene, especially few-layer graphene solid film, has been found to strongly suppress fluorescence and enhance Raman signals of probe molecules. In this paper, we attempt to explore the possibility of using graphene nanocolloids as potential substrates for the enhancement of Raman scattering. Graphene nanocolloids chemically produced from the reduction of graphene oxide by sodium citrate are nearly all monolayers in solution and are also found to exhibit certain surface-enhanced Raman scattering (SERS) activity to common aromatic probe molecules. Interestingly, largely different from few-layer graphene solid film, graphene nanocolloids show maximal SERS activity only when the probe molecules are at resonant laser excitation. According to our analysis, this phenomenon should arise from a combined effect of fluorescence quenching of graphene and a photoinduced charge transfer mechanism, in which the strong charge transfer accounts for the main contribution from close coupling between graphenes and probe molecules photoinduced by resonant excitation as well as the desolvation of graphene sheets and probe molecules.
石墨烯，特别是少层石墨烯固体薄膜，被发现能够强烈抑制探针分子的荧光并增强其拉曼信号。在本文中，我们试图探索将石墨烯纳米胶体用作增强拉曼散射的潜在基底的可能性。通过柠檬酸三钠还原氧化石墨烯化学合成的石墨烯纳米胶体在溶液中几乎全部为单层，并且对常见的芳香族探针分子也表现出一定的表面增强拉曼散射（SERS）活性。有趣的是，与少层石墨烯固体薄膜有很大不同，石墨烯纳米胶体仅在探针分子处于共振激光激发时表现出最大的 SERS 活性。根据我们的分析，这种现象应该源于石墨烯的荧光猝灭和光致电荷转移机制的综合作用，其中强电荷转移归因于共振激发诱导的石墨烯与探针分子之间的紧密耦合以及石墨烯片和探针分子的去溶剂化作用。
