Institute of Physics, National Academy of Sciences of Ukraine, 46 Nauki Ave, Kyiv 03680, Ukraine.
Institute of Physics, Center for Physical Sciences and Technology, A. Goštauto 11, Vilnius LT-01108, Lithuania.
Nanoscale Res Lett. 2014 May 27;9(1):263. doi: 10.1186/1556-276X-9-263. eCollection 2014.
Coherent anti-Stokes Raman scattering (CARS) of carbon nanostructures, namely, highly oriented pyrolytic graphite, graphene nanoplatelets, graphene oxide, and multiwall carbon nanotubes as well CARS spectra of thymine (Thy) molecules adsorbed on graphene oxide were studied. The spectra of the samples were compared with spontaneous Raman scattering (RS) spectra. The CARS spectra of Thy adsorbed on graphene oxide are characterized by shifts of the main bands in comparison with RS. The CARS spectra of the initial nanocarbons are definitely different: for all investigated materials, there is a redistribution of D- and G-mode intensities, significant shift of their frequencies (more than 20 cm(-1)), and appearance of new modes about 1,400 and 1,500 cm(-1). The D band in CARS spectra is less changed than the G band; there is an absence of 2D-mode at 2,600 cm(-1) for graphene and appearance of intensive modes of the second order between 2,400 and 3,000 cm(-1). Multiphonon processes in graphene under many photon excitations seem to be responsible for the features of the CARS spectra. We found an enhancement of the CARS signal from thymine adsorbed on graphene oxide with maximum enhancement factor about 10(5). The probable mechanism of CARS enhancement is discussed.
碳纳米结构的相干反斯托克斯拉曼散射（CARS），即高定向热解石墨、石墨烯纳米片、氧化石墨烯和多壁碳纳米管，以及吸附在氧化石墨烯上的胸腺嘧啶（Thy）分子的 CARS 光谱进行了研究。比较了样品的 CARS 光谱和自发拉曼散射（RS）光谱。与 RS 相比，吸附在氧化石墨烯上的 Thy 的 CARS 光谱的特征是主要带的位移。初始纳米碳的 CARS 光谱明显不同：对于所有研究的材料，D 带和 G 带的强度重新分配，其频率发生显著位移（超过 20 cm-1），并出现约 1400 和 1500 cm-1 的新模式。CARS 光谱中的 D 带比 G 带变化小；对于石墨烯，2600 cm-1 处没有 2D 模式，2400 和 3000 cm-1 之间出现强烈的二阶模式。在多光子激发下，石墨烯中的多声子过程似乎是 CARS 光谱特征的原因。我们发现吸附在氧化石墨烯上的胸腺嘧啶的 CARS 信号增强，最大增强因子约为 10（5）。讨论了 CARS 增强的可能机制。
