Angstrom-Scale Distance Dependence of Antenna-Enhanced Vibrational Signals
Angstrom-Scale Distance Dependence of Antenna-Enhanced Vibrational Signals
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DOI：
10.1021/nn304341c
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发表时间：
2012-12-01
期刊：
影响因子：
17.1
通讯作者：
Pucci, Annemarie
中科院分区：
文献类型：
--
作者：
Bochterle, Joerg;Neubrech, Frank;Pucci, Annemarie
共振增强近场的微米级金天线已探测到埃尺度的分辨率。在超高真空条件下冷凝聚在天线上的一氧化碳（0）层的原位表面增强红外光谱振动信号与平坦金表面上具有相应厚度的CO层的信号进行了比较。CO的振动信号以及等离子体共振频率的偏移被用来分析近场的距离依赖性。由天线引起的信号增强不仅从表面单调衰减，而且与经典的近场模型相反，在10和15埃之间显示出最大值，并且也朝向天线的表面衰减。这种效应归因于电子波函数的溢出，正如量子力学计算所预期的那样。
The resonantly enhanced near-field of micrometer-sized gold antennas has been probed with Angstrom-scale resolution. In situ surface-enhanced infrared spectroscopic vibrational signals of carbon monoxide ((0) layers cold-condensed on the antennas in ultrahigh-vacuum conditions are compared to the signals of CO layers with corresponding thicknesses on a flat gold surface. Vibrational signals of CO as well as the shift of the plasmonic resonance frequency were used to analyze the distance dependence of the near-field. The signal enhancement induced by the antennas not only decays monotonically from the surface but, in contrast to classical near-field models, shows a maximum between 10 and 15 angstrom and decays also toward the surface of the antenna. This effect is attributed to the spill-out of the electron wave function, as expected from quantum mechanical calculations.