Pushing the high-energy limit of plasmonics.

Bisio, Francesco; Proietti Zaccaria, Remo; Moroni, Riccardo; Maidecchi, Giulia; Alabastri, Alessandro; Gonella, Grazia; Giglia, Angelo; Andolfi, Laura et al. · ACS Nano · 2014

basic_science · Level V

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Abstract

The localized surface plasmon resonance of metal nanoparticles allows confining the eletromagnetic field in nanosized volumes, creating high-field "hot spots", most useful for enhanced nonlinear optical spectroscopies. The commonly employed metals, Au and Ag, yield plasmon resonances only spanning the visible/near-infrared range. Stretching upward, the useful energy range of plasmonics requires exploiting different materials. Deep-ultraviolet plasmon resonances happen to be achievable with one of the cheapest and most abundant materials available: aluminum indeed holds the promise of a broadly tunable plasmonic response, theoretically extending far into the deep-ultraviolet. Complex nanofabrication and the unavoidable Al oxidation have so far prevented the achievement of this ultimate high-energy response. A nanofabrication technique producing purely metallic Al nanoparticles has at last allowed to overcome these limits, pushing the plasmon resonance to 6.8 eV photon energy (≈180 nm) and thus significantly broadening the spectral range of plasmonics' numerous applications.