INVESTIGADORES
SCAFFARDI Lucia Beatriz
artículos
Título:
High spectral field enhancement and tunability in core-double shell metal-dielectric-metal spherical nanoparticles
Autor/es:
LUIS J. MENDOZA HERRERA; LUCÍA B. SCAFFARDI; DANIEL C. SCHINCA
Revista:
RSC Advances
Editorial:
RSC
Referencias:
Lugar: London - England; Año: 2016 vol. 6 p. 110471 - 110481
ISSN:
2046-2069
Resumen:
Core-double shell metal-dielectric-metal nanoparticles (NPs) have receivedmuch attention in the last years mainly due to its attractive property of multi-plasmon tunability, based on relative core-shell sizing. This kind of nanocomposites with several tens of nm in size has been fabricated in the form gold-silica-gold NPs for potential use in the biomedical area due to gold biocompatibility. Studies of these nanostructures use dipolar approximation or size-uncorrected metal dielectric function to analyze their multiply resonant plasmons.In this work we have developed full Mie theory for spherical core-double shellNPs, considering the continuity conditions of the electric and magnetic fields at each interface, to study plasmon resonances, optical extinction and spectral field enhancement of a generalized metal-dielectric-metal NPs. Keeping gold as the outer metal shell, calculations were carried out for different core metals (gold, silver, copper and aluminium) and different intermetallic dielectrics (silica, titanium dioxide, aluminium oxide and water). The metal dielectric function includes free and bound electron size corrections. Theoretical results show that the structures Al-SiO2-Au, Ag-SiO2-Au and Cu-SiO2-Au have field enhancement maxima factors of 33, 30 and 20 respectively in the outer region, all larger than that for Au-SiO2-Au. For the intermetallic region, field enhancement factors between 1000 and 800 are obtained for Ag-SiO2-Au and Cu-SiO2-Au, respectively, also larger than that for Au-SiO2-Au.Spatial field enhancement was also calculated for both regions, for different core metals and fixed core-double shell size. A hybridization model specially developed for a core-double shell system allows an insightful interpretation of its plasmon resonances, field enhancement maxima and lack of symmetry in the outer region field distribution.The tunability properties of field enhancement, dependent on relative coredoubleshell sizing, core metal and intermetallic dielectric permittivity, allows designing and engineering NPs with specific plasmonics resonances for enhancing nonlinear response of metallic nanocomposites with potential applications in harmonic generation, SERS and near field optics.