Scientific Results

Photo-induced heat generation in non-plasmonic nanoantennas

Year: 2018

Authors: Danesi S., Gandolfi M., Carletti L., Bontempi N., De Angelis C., Banfi F., Alessandri I.

Autors Affiliation: [Danesi, Stefano; Alessandri, Ivano] UdR Brescia, INSTM, Via Branze 38, I-2513 Brescia, Italy.
[Danesi, Stefano] Dept Mech & Ind Engn, Via Branze 38, I-2513 Brescia, Italy.
[Gandolfi, Marco; Banfi, Francesco] I LAMP, Via Musei 41, I-25121 Brescia, Italy.
[Gandolfi, Marco; Banfi, Francesco] Univ Cattolica Sacro Cuore, Dipartimento Matemat & Fis, Via Musei 41, I-25121 Brescia, Italy.
[Gandolfi, Marco] Katholieke Univ Leuven, Lab Soft Matter & Biophys, Dept Phys & Astron, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
[Carletti, Luca; De Angelis, Costantino; Alessandri, Ivano] Univ Brescia, Dept Informat Engn, Via Branze 38, I-2513 Brescia, Italy.
[Bontempi, Nicolo; De Angelis, Costantino; Alessandri, Ivano] CNR, INO, Via Branze 38, I-2513 Brescia, Italy.

Abstract: Light-to-heat conversion in non-plasmonic, high refractive index nanoantennas is a key topic for many applications, including Raman sensing, laser writing, nanofabrication and photo-thermal therapy. However, heat generation and propagation in non-plasmonic antennas is increasingly debated and contradictory results have been reported so far. Here we report a finite element analysis of the steady-state temperature distribution and heat flow in SiO2/Si core/shell systems (silicon nanoshells) irradiated with different continuous wave lasers (lambda = 532, 633 and 785 nm), under real working conditions. The complex interplay among the optical properties, morphology, degree of crystallinity of the nanoshells, thickness dependence of thermal conductivity and interactions with the substrate has been elucidated. This study reveals that all of these parameters can be appropriately combined for obtaining either stable nanoshells for Raman sensing or highly efficient sources of local heating. The optimal balance between thermal stability and field enhancement was found for crystalline Si shell layers with thicknesses ranging from 40 to 60 nm, irradiated by a NIR laser source. On the other hand, non-conformal amorphous or crystalline shell layers with a thickness >50 nm can reach a very high local temperature (above 1000 K) when irradiated with a low power density (less than 1 mW mu m(-2)) laser sources. This work provides a general approach for an extensive investigation of the opto-thermal properties of high-index nanoantennas.

Journal/Review: PHYSICAL CHEMISTRY CHEMICAL PHYSICS (PRINT)

Volume: 20 (22)      Pages from: 15307  to: 15315

More Information: Regione Lombardia. – This work was carried out in the framework of the project: ‘‘Microsfere adattative per il monitoraggio e l’abbattimento di inquinanti persistenti-MI ADATTI E L’ABBATTI’’ supported by INSTM and Regione Lombardia.
KeyWords: surface-enhanced spectroscopies; Raman-scattering; optical-properties; nanoparticles; nanoshells
DOI: 10.1039/c8cp01919c

Citations: 6
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English