Nanotechnology Research Laboratory, College of Engineering and Computer Science, The Australian National University, ACT, 2601, Australia.
Nonlinear Physics Centre, Research School of Physics and Engineering, The Australian National University, ACT, 2601, Australia.
Adv Mater. 2018 Jul;30(30):e1800931. doi: 10.1002/adma.201800931. Epub 2018 Jun 4.
Advances in the understanding and fabrication of plasmonic nanostructures have led to a plethora of unprecedented optoelectronic and optochemical applications. Plasmon resonance has found widespread use in efficient optical transducers of refractive index changes in liquids. However, it has proven challenging to translate these achievements to the selective detection of gases, which typically adsorb non-specifically and induce refractive index changes below the detection limit. Here, it's shown that integration of tailored fractals of dielectric TiO nanoparticles on a plasmonic metasurface strongly enhances the interaction between the plasmonic field and volatile organic molecules and provides a means for their selective detection. Notably, this superior optical response is due to the enhancement of the interaction between the dielectric fractals and the plasmonic metasurface for thickness of up to 1.8 μm, much higher than the evanescent plasmonic near-field (≈30 nm) . Optimal dielectric-plasmonic structures allow measurements of changes in the refractive index of the gas mixture down to <8 × 10 at room temperature and selective identification of three exemplary volatile organic compounds. These findings provide a basis for the development of a novel family of dielectric-plasmonic materials with application extending from light harvesting and photocatalysts to contactless sensors for noninvasive medical diagnostics.
等离子体纳米结构的理解和制造方面的进展带来了大量前所未有的光电和光化学应用。等离子体共振已广泛用于高效的液体折射率变化光学传感器。然而，将这些成果转化为气体的选择性检测一直具有挑战性，因为气体通常非特异性吸附并诱导低于检测限的折射率变化。在这里，研究表明在等离子体超表面上集成定制的介电 TiO2 纳米粒子的分形结构强烈增强了等离子体场与挥发性有机分子之间的相互作用，并为其选择性检测提供了一种手段。值得注意的是，这种优越的光学响应是由于在高达 1.8μm 的厚度范围内增强了介电分形结构和等离子体超表面之间的相互作用，远高于消逝的等离子体近场（≈30nm）。最佳的介电-等离子体结构允许测量室温下气体混合物的折射率变化低至<8×10-6，并能选择性地识别三种典型的挥发性有机化合物。这些发现为开发新型介电-等离子体材料提供了基础，其应用范围从光收集和光催化剂扩展到用于非侵入性医学诊断的非接触式传感器。
