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Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
摘要： Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets.
关键词： ethanol,water,SiO2 nanoparticles,photocatalysts,nanoparticles,Mie Monte-Carlo calculations,momentum-resolved photoionization,reaction nanoscopy,near-fields
更新于2025-09-19 17:13:59
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Impact of the Plasmonic Metal Oxide-Induced Photocatalytic Processes on the Interaction of Quantum Dots with Metallic Nanoparticles
摘要： We study plasmonic control of photocatalytic properties of metal oxides and the ways they influence interaction of quantum dots with metallic nanostructures. For this, gold nanostructures are coated with ultrathin layers of metal oxides (Al, Cu, Cr, or Ti oxide) and then covered with CdSe/ZnS quantum dots. The results show how the photocatalytic properties of such metal oxides are renormalized by plasmon near fields. In the cases of Al, Cr, and Ti oxides, the results mostly indicate the direct impact of plasmon fields via enhancement of optical excitations of the quantum dots. For the case of Cu oxide, however, the outcomes are found to be quite unique. In the absence of the plasmonic structures, such an oxide (CuO) presents highly active photocatalytic processes, leading to complete annihilation of the quantum dot emission. In the presence of the metallic nanostructures, the emission of such quantum dots is revived, offering an ultrafast decay process (～112 ps). These results indicate that in the case of CuO, the plasmonic metal oxide-induced photocatalytic processes include not only direct impact of plasmon near fields on the optical excitations of quantum dots but also the enhancement of interband transitions in CuO nanoparticles. The effects of energy transfer from quantum dots to metallic nanostructures and its equalization with Purcell effects on such processes are discussed.
关键词： ultrafast decay process,photocatalytic properties,plasmonic control,metallic nanostructures,Purcell effects,plasmon near fields,energy transfer,quantum dots,metal oxides
更新于2025-09-19 17:13:59