Dikkumbura Asela S, Hamal Prakash, Chen Min, Babayode Daniel A, Ranasinghe Jeewan C, Lopata Kenneth, Haber Louis H
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
J Phys Chem C Nanomater Interfaces. 2021 Nov 25;125(46):25615-25623. doi: 10.1021/acs.jpcc.1c06094. Epub 2021 Nov 15.
The growth dynamics of colloidal silver-gold core-shell (Ag@Au CS) nanoparticles (NPs) in water are monitored in a stepwise synthesis approach using time-dependent second harmonic generation (SHG) and extinction spectroscopy. Three sequential additions of chloroauric acid, sodium citrate, and hydroquinone are added to the silver nanoparticle solution to grow a gold shell around a silver core. The first addition produces a stable urchin-like surface morphology, while the second and third additions continue to grow the gold shell thickness as the surface becomes more smooth and uniform, as determined using transmission electron microscopy. The extinction spectra after each addition are compared to finite-difference time-domain (FDTD) calculations, showing large deviations for the first and second additions due to the bumpy surface morphology and plasmonic hotspots while showing general agreement after the third addition reaches equilibrium. The SHG signal is dominated by the NP surface, providing complementary information on the growth time scales due to changes to the surface morphology. This combined approach of synthesis and characterization of Ag@Au CS nanoparticles with SHG spectroscopy, extinction spectroscopy, and FDTD calculations provides a detailed foundation for investigating complex colloidal nanoparticle growth mechanisms and dynamics in developing enhanced plasmonic nanomaterial technologies.
采用随时间变化的二次谐波产生（SHG）和消光光谱法，以逐步合成的方式监测了水中胶体银金核壳（Ag@Au CS）纳米颗粒（NP）的生长动力学。向银纳米颗粒溶液中依次加入三次氯金酸、柠檬酸钠和对苯二酚，以在银核周围生长金壳。第一次添加产生了稳定的海胆状表面形态，而第二次和第三次添加随着表面变得更加光滑和均匀，继续增加金壳的厚度，这是通过透射电子显微镜确定的。每次添加后获得的消光光谱与有限时域差分（FDTD）计算结果进行比较，结果表明，由于表面形态崎岖不平和等离子体热点，第一次和第二次添加时存在较大偏差，而第三次添加达到平衡后则总体相符。SHG信号主要由NP表面决定，由于表面形态的变化，它提供了关于生长时间尺度的补充信息。这种结合了SHG光谱、消光光谱和FDTD计算的Ag@Au CS纳米颗粒合成与表征方法，为研究先进等离子体纳米材料技术中复杂的胶体纳米颗粒生长机制和动力学提供了详细的基础。
