Murai Shunsuke, Cabello-Olmo Elena, Kamakura Ryosuke, Calvo Mauricio E, Lozano Gabriel, Atsumi Taisuke, Míguez Hernán, Tanaka Katsuhisa
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Instituto de Ciencia de Materiales de Sevilla, Calle Américo Vespucio 49, 41092 Sevilla, Spain.
J Phys Chem C Nanomater Interfaces. 2020 Mar 12;124(10):5772-5779. doi: 10.1021/acs.jpcc.9b10999. Epub 2020 Feb 24.
Mesoporous silica features open and accessible pores that can intake substances from the outside. The combination of mesoporous silica with plasmonic nanostructures represents an interesting platform for an optical sensor based on the dependence of plasmonic modes on the refractive index of the medium in which metallic nanoparticles are embedded. However, so far only a limited number of plasmonic nanostructures are combined with mesoporous silica, including random dispersion of metallic nanoparticles and flat metallic thin films. In this study, we make a mesoporous silica layer on an aluminum nanocylinder array. Such plasmonic arrangements support both localized surface plasmon resonances (LSPRs) and extended modes which are the result of the hybridization of LSPRs and photonic modes extending into the mesoporous layer. We investigate optical reflectance of this system under controlled pressure of isopropanol vapor. Upon exposure, the capillary condensation in the mesopores results in a gradual spectral shift of the reflectance. Our analysis demonstrates that such shifts depend largely on the nature of the modes; that is, the extended modes show larger shifts compared to localized ones. Our materials represent a useful platform for the field of environmental sensing.
介孔二氧化硅具有开放且可进入的孔隙，能够从外部摄取物质。介孔二氧化硅与等离子体纳米结构的结合，基于等离子体模式对嵌入金属纳米颗粒的介质折射率的依赖性，为光学传感器提供了一个有趣的平台。然而，到目前为止，只有有限数量的等离子体纳米结构与介孔二氧化硅相结合，包括金属纳米颗粒的随机分散和平坦金属薄膜。在本研究中，我们在铝纳米圆柱阵列上制备了一层介孔二氧化硅。这种等离子体排列既支持局域表面等离子体共振（LSPR），也支持扩展模式，扩展模式是LSPR与延伸到介孔层中的光子模式杂交的结果。我们在异丙醇蒸汽的可控压力下研究了该系统的光学反射率。暴露后，介孔中的毛细管凝聚导致反射率的光谱逐渐偏移。我们的分析表明，这种偏移在很大程度上取决于模式的性质；也就是说，扩展模式比局域模式表现出更大的偏移。我们的材料为环境传感领域提供了一个有用的平台。
