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Sculpting Extreme Electromagnetic Field Enhancement in Free Space for Molecule Sensing
Small ( IF 13.0 ) Pub Date : 2018-07-12 , DOI: 10.1002/smll.201801146 Fanxin Liu 1, 2 , Boxiang Song 3 , Guangxu Su 1 , Owen Liang 4 , Peng Zhan 1 , Han Wang 3 , Wei Wu 3 , Yahong Xie 4, 5 , Zhenlin Wang 1
Small ( IF 13.0 ) Pub Date : 2018-07-12 , DOI: 10.1002/smll.201801146 Fanxin Liu 1, 2 , Boxiang Song 3 , Guangxu Su 1 , Owen Liang 4 , Peng Zhan 1 , Han Wang 3 , Wei Wu 3 , Yahong Xie 4, 5 , Zhenlin Wang 1
Affiliation
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A strongly confined and enhanced electromagnetic (EM) field due to gap‐plasmon resonance offers a promising pathway for ultrasensitive molecular detections. However, the maximum enhanced portion of the EM field is commonly concentrated within the dielectric gap medium that is inaccessible to external substances, making it extremely challenging for achieving single‐molecular level detection sensitivity. Here, a new family of plasmonic nanostructure created through a unique process using nanoimprint lithography is introduced, which enables the precise tailoring of the gap plasmons to realize the enhanced field spilling to free space. The nanostructure features arrays of physically contacted nanofinger‐pairs with a 2 nm tetrahedral amorphous carbon (ta‐C) film as an ultrasmall dielectric gap. The high tunneling barrier offered by ta‐C film due to its low electron affinity makes an ultranarrow gap and high enhancement factor possible at the same time. Additionally, its high electric permittivity leads to field redistribution and an abrupt increase across the ta‐C/air boundary and thus extensive spill‐out of the coupled EM field from the gap region with field enhancement in free space of over 103. The multitude of benefits deriving from the unique nanostructure hence allows extremely high detection sensitivity at the single‐molecular level to be realized as demonstrated through bianalyte surface‐enhanced Raman scattering measurement.
中文翻译：
塑造自由空间中分子传感的极端电磁场增强
由于间隙等离子体共振而产生的强限制和增强的电磁（EM）场为超灵敏分子检测提供了一条有前途的途径。然而，电磁场的最大增强部分通常集中在外部物质无法访问的介电间隙介质内，这使得实现单分子水平的检测灵敏度极具挑战性。在这里，介绍了通过使用纳米压印光刻的独特工艺创建的新系列等离子体激元纳米结构，该结构能够精确定制间隙等离子体激元，以实现增强的场溢出到自由空间。该纳米结构具有物理接触的纳米指对阵列，以及作为超小介电间隙的 2 nm 四面体非晶碳 (ta-C) 薄膜。 ta-C 薄膜由于其低电子亲和力而提供高隧道势垒，使得超窄能隙和高增强因子同时成为可能。此外，其高介电常数导致场重新分布和跨越ta-C/空气边界的突然增加，从而使耦合电磁场从间隙区域广泛溢出，自由空间中的场增强超过10 3 。通过双分析物表面增强拉曼散射测量证明，独特的纳米结构具有众多优点，可以在单分子水平上实现极高的检测灵敏度。
更新日期：2018-07-12
中文翻译：
塑造自由空间中分子传感的极端电磁场增强
由于间隙等离子体共振而产生的强限制和增强的电磁（EM）场为超灵敏分子检测提供了一条有前途的途径。然而，电磁场的最大增强部分通常集中在外部物质无法访问的介电间隙介质内，这使得实现单分子水平的检测灵敏度极具挑战性。在这里，介绍了通过使用纳米压印光刻的独特工艺创建的新系列等离子体激元纳米结构，该结构能够精确定制间隙等离子体激元，以实现增强的场溢出到自由空间。该纳米结构具有物理接触的纳米指对阵列，以及作为超小介电间隙的 2 nm 四面体非晶碳 (ta-C) 薄膜。 ta-C 薄膜由于其低电子亲和力而提供高隧道势垒，使得超窄能隙和高增强因子同时成为可能。此外，其高介电常数导致场重新分布和跨越ta-C/空气边界的突然增加，从而使耦合电磁场从间隙区域广泛溢出，自由空间中的场增强超过10 3 。通过双分析物表面增强拉曼散射测量证明，独特的纳米结构具有众多优点，可以在单分子水平上实现极高的检测灵敏度。
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