研究目的
To investigate the size and dimension dependent surface-enhanced Raman scattering properties of well-defined Ag nanocubes, including their synthesis, self-assembly, and quantitative analysis of SERS activity.
研究成果
The study successfully synthesized Ag nanocubes with a wide size range and demonstrated that SERS activity depends on the matching of nanocube size to excitation wavelength, with optimal sizes identified. Hierarchical nanostructures showed increased Raman enhancement from 0D to 3D due to additional hot spots from plasmonic coupling. This provides a foundation for designing high-sensitivity SERS substrates and suggests applications in other spectroscopic techniques.
研究不足
The size distribution of Ag nanocubes broadened with increasing size, and the synthesis of cubes larger than 500 nm required additional steps to avoid shape variations. The multiple coupling effects in SERS measurements complicated the correlation with UV-vis spectra. The penetration depth of incident light limited the enhancement in thicker 3D nanostructures.
1:Experimental Design and Method Selection:
A multistep seed-mediated polyol reduction method was used to synthesize Ag nanocubes with sizes from 50 to 1400 nm. SERS substrates were prepared by self-assembling nanocubes on Au films or silicon wafers, and FDTD calculations were employed for simulation.
2:Sample Selection and Data Sources:
Ag nanocubes were synthesized using silver nitrate, poly(vinylpyrrolidone), and solvents like 1,5-pentanediol and ethylene glycol. Probe molecules included 4-mercaptobenzoic acid (MBA), 1,4-benzenedithiol (1,4-BDT), and malachite green.
3:List of Experimental Equipment and Materials:
Scanning electron microscopy (SEM, Hitachi S-4800), transmission electron microscopy (TEM, Hitachi H-7650), UV-Vis spectrometer (Shimadzu UV-Vis 2550), Raman spectrometer (Horiba XploRA), lasers at 532 nm, 638 nm, and 785 nm wavelengths, and chemicals from suppliers like Sigma-Aldrich and Shanghai Reagent Corporation.
4:Experimental Procedures and Operational Workflow:
Synthesis involved heating and injecting precursor solutions, followed by quenching. SERS substrates were prepared by depositing nanocube monolayers on Au films or silicon wafers, adsorbing probe molecules, and measuring Raman spectra. FDTD simulations were conducted using Lumerical FDTD solutions software.
5:Data Analysis Methods:
SERS intensities were averaged from multiple spots, enhancement factors were calculated, and statistical analysis was performed on nanoparticle sizes and interparticle distances.
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