Topic
Femtosecond
About: Femtosecond is a research topic. Over the lifetime, 35106 publications have been published within this topic receiving 691405 citations. The topic is also known as: 1 E-15 s & fs.
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TL;DR: In this article, the photochemistry of trans-azobenzene in n-hexane was studied using femtosecond time-resolved UV-visible absorption spectroscopy.
215 citations
TL;DR: In this article, a single-shot visualization of laser-wakefield accelerator structures is presented, which captures the evolution of multiple wake periods, detect structure variations as laser-plasma parameters change, and resolve wavefront curvature.
Abstract: Tabletop plasma accelerators can now produce GeV-range electron beams1,2,3,4,5 and femtosecond X-ray pulses6, providing compact radiation sources for medicine, nuclear engineering, materials science and high-energy physics7. In these accelerators, electrons surf on electric fields exceeding 100 GeV m−1, which is more than 1,000 times stronger than achievable in conventional accelerators. These fields are generated within plasma structures (such as Langmuir waves8 or electron density ‘bubbles’9) propagating near light speed behind laser2,3,4 or charged-particle5 driving pulses. Here, we demonstrate single-shot visualization of laser-wakefield accelerator structures for the first time. Our ‘snapshots’ capture the evolution of multiple wake periods, detect structure variations as laser–plasma parameters change, and resolve wavefront curvature; features never previously observed.
215 citations
TL;DR: Amplitude- and phase-resolved ultrafast transmission experiments directly reveal the coherent coupling between surface plasmon polaritons induced by periodic variations in the dielectric function, leading to the first observation of subradiance in plAsmonic nanocrystals.
Abstract: We report the first observation of subradiance in plasmonic nanocrystals. Amplitude- and phase-resolved ultrafast transmission experiments directly reveal the coherent coupling between surface plasmon polaritons (SPPs) induced by periodic variations in the dielectric function. This interaction results in the formation of plasmonic band gaps and coupled SPP eigenmodes with different symmetries, as directly shown by near-field imaging. In antisymmetric modes, radiative SPP damping is strongly suppressed, increasing the SPP lifetime from 30 fs to more than 200 fs. The findings are analyzed within a coupled resonance model.
215 citations
TL;DR: In this paper, the influence of different laser parameters (pulse energy, pulse overlap) and properties of media (air, airbrush, water) on the rate of production and size distribution of the laser-generated nanoparticles was determined.
Abstract: Femtosecond laser ablation is used to generate nanoparticle aerosols and colloids from solid targets of various materials (Ti, Ag, Au, Co, etc.) in air and water ambience. We determine the influence of different laser parameters (pulse energy, pulse overlap) and properties of media (air, airbrush, water) on the rate of production and size distribution of the laser-generated nanoparticles. It is shown that the pulse overlap and laser fluence are the parameters determining the nanoparticle size. At optimum conditions the nanoparticle productivity can be increased by 150–300%. The generation of multimaterial nanoparticle dispersions is demonstrated. Being free of toxic impurities, the laser-produced nanoparticles may be promising for biomedical applications.
215 citations
TL;DR: In this paper, the fundamental mechanical radial mode of silver nanoparticles is coherently excited and probed via its interaction with the electron gas, and the mechanical oscillations are launched by an indirect displacive process and are detected via the induced modulation of the surface plasmon resonance frequency.
Abstract: Using a femtosecond pump-probe technique, the fundamental mechanical radial mode of silver nanoparticles is coherently excited and probed via its interaction with the electron gas. The mechanical oscillations are launched by an indirect displacive process and are detected via the induced modulation of the surface plasmon resonance frequency. The measured fundamental radial mode period and damping time are found to be proportional to the nanoparticle radius in the range of 3–15 nm, in agreement with theoretical predictions.
214 citations