Plasmon resonances tailored by Fano profiles in silver-based core–shell nanoparticles. Issue 5 (18th January 2016)

• Record Type: Journal Article
• Authors: Pellarin, Michel; Broyer, Michel; Lermé, Jean; Lebeault, Marie-Ange; Ramade, Julien; Cottancin, Emmanuel
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 5(2016)
• Page Start: 4121
• Page End: 4133
• Publication Date: 2016-01-18
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c5cp07113e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The generic optical absorption band of core–shell M@Ag nanoparticles observed in many experiments is rationalized through the formation of a Fano-like profile originating from the coupling between the silver shell LSPR and the core interband absorption continuum. Abstract : The optical absorption of bimetallic nanoparticles M–Ag involving silver as an active plasmonic compound has been the subject of very extensive experimental studies, both for a large range of sizes and a large variety of associated metals. Considering the most commonly encountered core–shell segregated configuration M@Ag involving a transition metal M, the spectral response is found to be weakly discriminating with regard to the chemical order and composition and is characterized by a large unstructured plasmon resonance in the 2 eV to 4 eV range. The plasmon band is essentially shaped by the scars made in the absorption continuum of metal M by Fano-like induced resonances and is surprisingly little sensitive to the exact nature of this metal, giving birth to a "quasi universal" optical signature for M@Ag systems. In this paper, we show how this generic behaviour arises from the specific plasmonic response of silver and stress the role of interband transitions of both metals through their coupling with the free electron oscillation modes. This theoretical discussion will be illustrated through selected experimental results.