金纳米空心半球壳膜的可调谐光学性质研究

以单层聚苯乙烯微球阵列为模板,通过控制其表面金膜蒸镀时间,制备了具有不同厚度的空心半球壳结构的金纳米膜.利用扫描电子显微镜和自制光谱仪分别测量了金膜表面形貌和其透射光谱,并分析了金膜形貌与其光学性质间的关系,同时以4-巯基苯胺为探针分子测定了金膜的表面增强喇曼散射效应.结果表明,该金纳米膜的表面等离子体共振波长随膜厚度增大而发生红移,在可见与近红外波段较宽范围内可调谐,并且,当金膜共振波长与入射激发光波长较近时,探针分子可产生出较强的表面增强喇曼信号.同时,对该现象的产生机制也进行了理论解释.

Tunable Plasmonic Properties of Gold Hollow-core Semi-shell Nanofilms

The gold hollow-core semi-shell nanofilms with different thicknesses were fabricated by depositing gold onto a cleaned glass support covered with a close-packed monolayer of 200 nm diameter polystyrene spheres and subsequently by the removal of the PS spheres. The thicknesses of gold nanofilms can be controlled by the deposition time, the morphologies and optical properties of gold films were obtained by field emission scanning electron microscopy and home-built spectrometer respectively, and the relationship between morphologies and tunable plasmonic properties was also discussed. Then, using 4-aminothiophenol (4-ATP) as the probe molecule, the surface enhanced Raman scattering signals of 4-ATP adsorbed on the films after immersing the nanofilms into the 4-ATP solution were measured by Raman spectrometer with the excitation wavelength of 785 nm. The results show that the localized surface plasmon resonance wavelength of gold nanofilm red shifts as the film thickness increases, and the resonance wavelength can be tuned over a wide range from visible band to infra-red band; moreover, when the resonance wavelength of nanofilms is close to the incident excitation wavelength, the surface enhanced Raman scattering signals can be obtained obviously, indicating that the fabricated nanofilms can be used as the potential surface enhanced Raman substrates. The reasons of the shift of the spectral peak and SERS intensity of different nanofilms were also discussed.