Schmidt Franz-Philipp, Losquin Arthur, Horák Michal, Hohenester Ulrich, Stöger-Pollach Michael, Krenn Joachim R
Institute of Physics, University of Graz, Universitätsplatz 5, Graz 8010, Austria.
Thales Research and Technology, 1 avenue Augustin Fresnel, Palaiseau 91767, France.
Nano Lett. 2021 Jan 13;21(1):590-596. doi: 10.1021/acs.nanolett.0c04084. Epub 2020 Dec 18.
We use cathodoluminescence (CL) spectroscopy in a transmission electron microscope to probe the radial breathing mode of plasmonic silver nanodisks. A two-mirror detection system sandwiching the sample collects the CL emission in both directions, that is, backward and forward with respect to the electron beam trajectory. We unambiguously identify a spectral shift of about 8 nm in the CL spectra acquired from both sides and show that this asymmetry is induced by the electron beam itself. By numerical simulations, we confirm the observations and identify the underlying physical effect due to the interference of the CL emission patterns of an electron-beam-induced dipole and the breathing mode. This effect can ultimately limit the achievable fidelity in CL measurements on any system involving multiple excitations and should therefore be considered with care in high-precision experiments.
我们在透射电子显微镜中使用阴极发光（CL）光谱来探测等离子体银纳米盘的径向呼吸模式。一个夹着样品的双镜检测系统在两个方向上收集CL发射，即相对于电子束轨迹向后和向前。我们明确地识别出从两侧获取的CL光谱中约8nm的光谱位移，并表明这种不对称是由电子束本身引起的。通过数值模拟，我们证实了这些观察结果，并确定了由于电子束诱导偶极子的CL发射模式与呼吸模式的干涉而产生的潜在物理效应。这种效应最终可能会限制在任何涉及多个激发的系统中CL测量可实现的保真度，因此在高精度实验中应谨慎考虑。
