研究目的
Investigating the decomposition kinetics of 5-Bromouracil (BrU) in the vicinity of gold nanoparticles (AuNPs) illuminated with intense nanosecond laser pulses under various conditions.
研究成果
The decomposition rates for the fragmentation of the BrU ring structure depend on the fluence, the repetition rate of the laser, and the starting concentration of BrU. The cleavage of the C–Br bond leaving the residual molecule intact is most likely independent of the adsorption of the molecules on the AuNPs. The irradiation parameters are interlinked with the optical and thermal properties of the generated AuNP substrates, limiting the tunability of the reaction kinetics of the system.
研究不足
The study is limited by the trade-off between laser fluence and plasmonic response of the AuNPs due to their size reduction under irradiation. The conditions directly on the AuNP surface are extreme in terms of temperature and pressure, which might affect the reaction pathways.
1：Experimental Design and Method Selection:
The study used ultraviolet and visible (UV–Vis) spectroscopy to track the plasmonic response of AuNPs and the concentration of BrU and resulting photoproducts as a function of irradiation time. A kinetic model was developed to determine the reaction rates of two parallel fragmentation pathways of BrU.
2：Sample Selection and Data Sources:
AuNPs with 40 nm average diameter and BrU dissolved in ultrapure water were used. The samples were irradiated with ns laser pulses at 532 nm.
3：List of Experimental Equipment and Materials:
A Minilite I (Continuum) Nd:YAG laser, a Jasco 650 spectrophotometer, and an Agilent 5500 atomic force microscope (AFM) were used.
4：Experimental Procedures and Operational Workflow:
The laser beam was focused on a quartz cuvette filled with the AuNP/BrU solution. UV–Vis spectra were recorded after specific illumination times. AFM was used to image dried AuNPs.
5：Data Analysis Methods:
The size distribution of the AuNPs was determined from AFM images. The reaction rates were determined from the UV–Vis spectra using a kinetic model.
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