### 水溶液中碳纳米管的表面增强拉曼光谱研究

1. 北京大学化学与分子工程学院 北京分子科学国家实验室 纳米器件物理与化学教育部重点实验室 稀土材料化学及应用国家重点实验室 北京 100871
• 收稿日期:2012-05-11 出版日期:2012-07-28 发布日期:2012-06-19
• 通讯作者: 李彦
• 基金资助:

项目受科技部(No. 2011CB933003)和国家自然科学基金(Nos. 21125103, 11179011)资助.

### Surface-Enhanced Raman Spectroscopy of Carbon Nanotubes in Aqueous Solution

Niu Yang, Liu Qinghai, Yang Juan, Gao Dongliang, Qin Xiaojun, Luo Da, Zhang Zhenyu, Li Yan

1. Beijing National Laboratory for Molecular Sciences, Key Laboratory for the Physics and Chemistry of Nanodevices, State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871, China
• Received:2012-05-11 Online:2012-07-28 Published:2012-06-19
• Supported by:

Project supported by the Ministry of Science and Technology of China (No. 2011CB933003) and the National Natural Science Foundation of China (Nos. 21125103, 11179011).

Carbon nanotubes (CNTs) exhibit intrinsic spectroscopic properties and are potential Raman and NIR florescence probes for bioimaging. However, the weak Raman intensity greatly obstructs such applications. Surface-enhanced Raman scattering (SERS) has shown to be an effective way to increase the Raman signal. SERS has been widely studied for solid samples. However, solid state is distinctly different from the environment in biosystems. Herein, we studied the SERS of Au- nanoparticle-decorated CNTs in aqueous solution, which offers a similar environment to biosystems. We found that the functionalization of CNTs with-SH groups can improve the attachment of Au nanoparticles on tube surfaces thus benefit the SERS effect. The particle size is another important issue for SERS. Particles of 50 nm show much stronger enhancement than those of 12 nm. The Raman intensity of CNTs increases with the increase of the concentration of Au nanoparticles. Hexamethylene diamine molecules can act as the bi-linkers between Au nanoparticles, compressing the interparticle distance. This was proved by the red-shift of the band at ca. 540 nm and the appearance of a broad band around 700 nm in the absorption spectra of Au nanoparticles. Therefore the addition of hexamethylene diamine can further increase the Raman signal of CNTs by the strong coupling of the surface plasma from the Au nanoparticles with very small interparticle distances. Two kinds of commonly used small molecule Raman probes p-aminothiophenol and Rhodamine B both show remarkably enhanced Raman intensity when added to the aqueous dispersion of Au/CNT hybrids. This shows that these Raman probe molecules can absorb onto the Au/CNT hybrids and their Raman spectra are able to be greatly enhanced by Au nanoparticles decorated on CNTs. Because various Raman bands from either CNTs or Raman probe molecules can be used for Raman imaging, this kind of Raman probe molecule/Au/CNT tri-component hybrid systems may be used as a potential nanostructured platform for multiplexed Raman imaging based on SERS effect.