Transient localized surface plasmon induced by femtosecond interband excitation in gold nanoparticles

Localized surface plasmon resonance (LSPR) is essentially a collective oscillation of free electrons in nanostructured metals. Interband excitation may also produce conduction-band electrons above the Fermi level. However, a question here is whether these excited electrons can take part in plasmonic...

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Bibliographic Details
Published in:Scientific reports 2018-07, Vol.8 (1), p.10499-7, Article 10499
Main Authors: Zhang, Xinping, Huang, Cuiying, Wang, Meng, Huang, Pei, He, Xinkui, Wei, Zhiyi
Format: Article
Language:English
Subjects:
140/125
639/624/400/1021
639/925/357/354
Absorption spectroscopy
Conduction
Gold
Heavy metals
Humanities and Social Sciences
multidisciplinary
Nanoparticles
Science
Science (multidisciplinary)
Spectrum analysis
Surface plasmon resonance
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Summary:Localized surface plasmon resonance (LSPR) is essentially a collective oscillation of free electrons in nanostructured metals. Interband excitation may also produce conduction-band electrons above the Fermi level. However, a question here is whether these excited electrons can take part in plasmonic oscillation. To answer this question, femtosecond pump-probe measurements on gold nanoparticles were performed using interband excitation, where the pump pulse produced a large amount of electrons in the sp -conduction band and left holes in the d -band. Probing by transient absorption spectroscopy, we resolved an induced LSPR feature located at a red-shifted spectrum. This feature cannot be observed for a pumping photon energy lower than the threshold for interband transition. The commonly observed red-shift or broadening of LSPR spectrum due to electron-electron and electron-phonon scattering under strong optical excitation can be ruled out for understanding this feature by a comparison between the plasmonic dynamics at a pump above and below the interband-transition threshold. In particular, a “holding” time of about 1 ps was resolved for the interband-excitation-induced electrons to relax to the LSPR oscillation.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-28909-6