CIC nanoGUNE Consolider, 20018 Donostia-San Sebastián, Spain.
Nat Commun. 2012 Feb 21;3:684. doi: 10.1038/ncomms1674.
Light scattering at nanoparticles and molecules can be dramatically enhanced in the 'hot spots' of optical antennas, where the incident light is highly concentrated. Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally. Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process. We provide experimental evidence that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering. We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering.
在光学天线的“热点”处，纳米粒子和分子的光散射可以显著增强，在热点处，入射光高度集中。尽管这种效应在表面增强光学传感、光谱学和显微镜学中得到了广泛应用，但信号增强的潜在电磁机制在实验上很难追踪。在这里，我们研究了位于单个天线定义明确的热点中的单个物体的弹性散射光，这是一种新的方法，可以确定天线在散射过程中的作用。我们提供了实验证据，证明从物体弹性散射的光的强度与天线提供的局部场增强的四次方成正比，并且潜在的电磁机制与在表面增强拉曼散射中普遍接受的机制相同。我们还测量了散射光的相移，这提供了表面增强光散射的一种新颖而明确的指纹。
