Bontempi Nicolò, Vassalini Irene, Danesi Stefano, Ferroni Matteo, Donarelli Maurizio, Colombi Paolo, Alessandri Ivano
INSTM-UdR Brescia , via Branze 38 , 25123 Brescia , Italy.
INO-CNR , via Branze 38 , 25123 Brescia , Italy.
J Phys Chem Lett. 2018 May 3;9(9):2127-2132. doi: 10.1021/acs.jpclett.8b00662. Epub 2018 Apr 16.
Silicon is one of the most interesting candidates for plasmon-free surface-enhaced Raman scattering (SERS), because of its high-refractive index and thermal stability. However, here we demonstrate that the alleged thermal stability of silicon nanoshells irradiated by conventional Raman laser cannot be taken for granted. We investigated the opto-thermal behavior of SiO/Si core/shell microbeads (Si-rex) irradiated with three common Raman laser sources (λ = 532, 633, 785 nm) under real working conditions. We obtained an experimental proof of the critical role played by bead size and aggregation in heat and light management, demonstrating that, in the case of strong opto-thermal coupling, the temperature can exceed that of the melting points of both core and shell components. In addition, we also show that weakly coupled beads can be utilized as stable substrates for plasmon-free SERS experiments.
硅因其高折射率和热稳定性，是无等离子体表面增强拉曼散射（SERS）最具吸引力的候选材料之一。然而，我们在此证明，传统拉曼激光照射下的硅纳米壳所谓的热稳定性并非理所当然。我们研究了在实际工作条件下，用三种常见拉曼激光源（λ = 532、633、785 nm）照射的SiO/Si核壳微珠（Si-rex）的光热行为。我们获得了实验证据，证明珠子尺寸和聚集在热和光管理中所起的关键作用，表明在强光热耦合的情况下，温度可能超过核和壳成分的熔点。此外，我们还表明，弱耦合珠子可作为无等离子体SERS实验的稳定基底。
