Geometry and crystallinity play a critical role in the wavelength-dependent optical responses and plasmonic local near-field distributions of metallic nanostructures. Nevertheless, the ability to tailor the shape and position of crystalline metal surface nanostructures has remained a challenge that limits control of their enhanced local fields and represents a barrier to harnessing their individual and collective responses. Here, we describe a solution deposition method in the presence of anionic additives, which yields shape-controlled, single-crystal plasmonic gold nanostructures on Ag(100) and Au(100) substrates. Use of SO₄^2– ions yields smooth Au(111)-faceted square pyramids with large plasmonic Raman enhancements. Halide additives produce textured hillocks comprising edge- and screw-type dislocations (Cl^–), or platelets with large-area Au(100) terraces and (110) step edges (Br^–), while SO₄^2– and Br^– additive combinations provide Au(110)-faceted square pyramids. With lithographic patterning, this chemistry yields metal deposition with precise geometry and location control to provide single-crystal, plasmonic gold metasurfaces with tailored optical response. The appropriately designed metasurfaces can then generate large Raman scattering enhancements, far greater than high density gold square pyramids with random surface disposition. Shape-controlled single-crystal plasmonic metasurfaces will thus offer opportunities to tune the characteristics of nanostructures, providing enhanced optical, photocatalytic, and sensory response.

中文翻译：

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用形状控制的单晶金超表面定制等离子体场


几何形状和结晶度在金属纳米结构的波长相关光学响应和等离子体局部近场分布中起着至关重要的作用。然而，定制晶体金属表面纳米结构的形状和位置的能力仍然是一个挑战，它限制了对其增强的局部场的控制，并成为利用其个人和集体反应的障碍。在这里，我们描述了一种在阴离子添加剂存在下的溶液沉积方法，该方法在 Ag(100) 和 Au(100) 基底上产生形状控制的单晶等离子体金纳米结构。使用 SO ₄ ^2– 离子可产生光滑的 Au(111) 面方锥体，具有较大的等离子体拉曼增强效果。卤化物添加剂可产生包含边缘型和螺旋型位错 (Cl ^– ) 的纹理小丘，或具有大面积 Au(100) 阶地和 (110) 阶梯边缘的片晶 (Br ^– ），而 SO ₄ ^2– 和 Br ^– 添加组合提供 Au(110) 面方锥体。通过光刻图案化，这种化学反应可产生具有精确几何形状和位置控制的金属沉积，以提供具有定制光学响应的​​单晶等离子体金超表面。适当设计的超表面可以产生大的拉曼散射增强，远远大于具有随机表面配置的高密度金方金字塔。因此，形状控制的单晶等离子体超表面将提供调整纳米结构特性的机会，从而提供增强的光学、光催化和感官响应。