Cathodoluminescence in Ultrafast Electron Microscopy

Abstract

Implementing the modern technologies of light-emitting devices, light harvesting, and quantum information processing requires the understanding of the structure–function relations at spatial scales below the optical diffraction limit and time scales of energy and information flows. Here, we distinctively combine cathodoluminescence (CL) with ultrafast electron microscopy (UEM), termed CL-UEM, because CL and UEM synergetically afford the required spectral and spatiotemporal sensitivities, respectively. For color centers in nanodiamonds, we demonstrate the measurement of CL lifetime with a local sensitivity of 50 nm and a time resolution of 100 ps. It is revealed that the emitting states of the color centers can be populated through charge transfer among the color centers across diamond lattices upon high-energy electron beam excitation. The technical advance achieved in this study will facilitate the specific control over energy conversion at nanoscales, relevant to quantum dots and single-photon sources.

Progress and Prospects in Optical Ultrafast Microscopy in the Visible Spectral Region: Transient Absorption and Two-Dimensional Microscopy

“…197 UEM has further been combined with cathodoluminescence (CL-UEM), wherein the optical excitation beam is turned off and the electron beam is used to excite the sample, with the resulting cathodoluminescence recorded by a single photon counter which is timecorrelated with the electron pulse. 198,199 UEM has been employed to image and study acoustic vibration dynamics in single nanoparticles, 200,201 identify active sites in inorganic photocatalysts, 202 and probe the dynamics of the electronic states of nitrogen color centers in nanodiamonds in both transmission and scanning transmission modes. 198,199 In another variant of UEM, called ultrafast spectrum imaging (USI), Yurtsever et al used the optical excitation mechanism to increase the spectral resolution compared to conventional electron energy loss spectroscopy and measured spectral images of silver nanoparticles and copper interfaces.…”

“…These pulses contain single or very few electrons such that the mutual Coulomb repulsion between electrons, which would result in temporal spread, is negligible, and images are collected stroboscopically . UEM has further been combined with cathodoluminescence (CL-UEM), wherein the optical excitation beam is turned off and the electron beam is used to excite the sample, with the resulting cathodoluminescence recorded by a single photon counter which is time-correlated with the electron pulse. , …”

“…UEM has been employed to image and study acoustic vibration dynamics in single nanoparticles, , identify active sites in inorganic photocatalysts, and probe the dynamics of the electronic states of nitrogen color centers in nanodiamonds in both transmission and scanning transmission modes. , In another variant of UEM, called ultrafast spectrum imaging (USI), Yurtsever et al used the optical excitation mechanism to increase the spectral resolution compared to conventional electron energy loss spectroscopy and measured spectral images of silver nanoparticles and copper interfaces . Furthermore, photon-induced near-field EM (PINEM) forms images through electrons that have gained energy following optical excitation .…”

Effect of Particle Size on the Optical Properties of Silicon‐Vacancy Centers in Nanodiamonds Fabricated by a Detonation Process

“…As shown in a previous investigation of NV centers, the luminescence lifetime of the color centers in NDs is known to slightly differ among individual particles and exhibits a certain distribution. [56,57] 3.2.5. Effect of Particle Size on the Optical Properties of SiV Centers in DNDs…”

Characterizing an Optically Induced Sub-micrometer Gigahertz Acoustic Wave in a Silicon Thin Plate

“…Recent development of ultrafast transmission electron microscopy opens a novel pathway to the direct observation of strain dynamics on nm × ps resolution. − Indeed, acoustic waves emitted from unintentional defects and sample edges in free-standing flake samples are observed in the literature. ,, However, the characterization of acoustic waves fully considering the dispersion relation and multimode nature in a finite size system has been limited in such samples. Here we characterize the nanoplate waves in a well-designed nanofabricated ultrathin plate and compare them with theoretical simulations.…”