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Infrared plasmonics: STEM-EELS characterization of Fabry-P??rot resonance damping in gold nanowires
摘要： Materials possessing strong midinfrared responses are of current interest because of their potential application to long-wavelength metamaterials, photonic devices, molecular detection, and catalysis. Here, we utilize high-energy resolution (80 cm?1, 10 meV) electron-energy-loss spectroscopy (EELS) in a monochromated and aberration-corrected scanning transmission electron microscope (STEM) to resolve multipolar surface plasmon resonances (SPRs), sometimes called Fabry-Pérot (FP) resonances, in gold nanowires with mode energies spanning from ～1000 to 8000 cm?1. STEM-EELS provides access to these mid- to near-IR responses in a single acquisition, avoiding the difficulties inherent in obtaining the same data using near-field optical techniques. The experimentally measured FP resonance energies and linewidths, together with analytical modeling and full-wave numerical electrodynamics simulations, provide a comprehensive picture of the radiative and intrinsic contributions to the total damping rates. We find some FP modes with dephasing times >60 fs, which is almost twice the longest previously reported plasmon dephasing time for individual Au nanoparticles in the infrared. The long dephasing times and the broad tunability of the FP resonance energies throughout the infrared region suggest additional opportunities for harnessing infrared plasmonic energy before dephasing occurs.
关键词： gold nanowires,plasmon dephasing times,Fabry-Pérot resonance,infrared plasmonics,STEM-EELS
更新于2025-09-23 15:19:57
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Characterization of ultrafast plasmon dynamics in individual gold bowtie by time-resolved photoemission electron microscopy
摘要： We report on the investigation of ultrafast dynamics of the plasmonic field in individual gold bowtie nanostructure by combining interferometric time-resolved photoemission electron microscopy with a damped harmonic oscillator model. We experimentally obtain different plasmon dephasing times in the tips of the bowtie nanostructure. In the meantime, we demonstrate that the experimental time-resolved photoemission signal can be used to directly compare resonance frequency and dephasing time of different hot spots. In addition, we find that the plasmon field, which is extracted from the photoemission signal, initially oscillates at the laser field frequency, and finally develops into its eigenfrequency after experiencing a few periods of frequency fluctuation due to the competition between forced and autonomous oscillation of the plasmons.
关键词： ultrafast plasmon dynamics,gold bowtie,resonance frequency,plasmon dephasing times,time-resolved photoemission electron microscopy
更新于2025-09-09 09:28:46