Zhu Yun-Pei, El-Demellawi Jehad K, Yin Jun, Lopatin Sergei, Lei Yongjiu, Liu Zhixiong, Miao Xiaohe, Mohammed Omar F, Alshareef Husam N
Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
Adv Mater. 2020 May;32(19):e1908392. doi: 10.1002/adma.201908392. Epub 2020 Mar 23.
Developing stable plasmonic materials featuring earth-abundant compositions with continuous band structures, similar to those of typical metals, has received special research interest. Owing to their metal-like behavior, monoclinic MoO nanostructures have been found to support stable and intense surface plasmon (SP) resonances. However, no progress has been made on their energy and spatial distributions over individual nanostructures, nor the origin of their possibly existing specific SP modes. Here, various MoO nanostructures are designed via polydopamine chemistry and managed to visualize multiple longitudinal and transversal SP modes supported by the monoclinic MoO , along with intrinsic interband transitions, using scanning transmission electron microscopy coupled with ultrahigh-resolution electron energy loss spectroscopy. The identified geometry-dependent SP energies are tuned by either controlling the shape and thickness of MoO nanostructures through their well-designed chemical synthesis, or by altering their length using a developed electron-beam patterning technique. Theoretical calculations reveal that the strong plasmonic behavior of the monoclinic MoO is associated with the abundant delocalized electrons in the Mo d orbitals. This work not only provides a significant improvement in imaging and tailoring SPs of nonconventional metallic nanostructures, but also highlights the potential of MoO nanostructures for micro-nano optical and optoelectronic applications.
开发具有与典型金属类似的连续能带结构且成分富含地球元素的稳定等离子体材料，已引起了特别的研究兴趣。由于其类似金属的行为，人们发现单斜相MoO纳米结构能够支持稳定且强烈的表面等离子体（SP）共振。然而，对于它们在单个纳米结构上的能量和空间分布，以及可能存在的特定SP模式的起源，尚未取得任何进展。在此，通过聚多巴胺化学方法设计了各种MoO纳米结构，并利用扫描透射电子显微镜与超高分辨率电子能量损失谱相结合的技术，成功地可视化了单斜相MoO所支持的多种纵向和横向SP模式，以及本征带间跃迁。通过精心设计化学合成来控制MoO纳米结构的形状和厚度，或者使用先进的电子束图案化技术改变其长度，从而调整所确定的与几何形状相关的SP能量。理论计算表明，单斜相MoO的强等离子体行为与Mo d轨道中丰富的离域电子有关。这项工作不仅在成像和定制非常规金属纳米结构的SP方面取得了显著进展，还突出了MoO纳米结构在微纳光学和光电子应用中的潜力。
