Coincidence Detection of EELS and EDX Spectral Events in the Electron Microscope

Abstract

Recent advances in the development of electron and X-ray detectors have opened up the possibility to detect single events from which its time of arrival can be determined with nanosecond resolution. This allows observing time correlations between electrons and X-rays in the transmission electron microscope. In this work, a novel setup is described which measures individual events using a silicon drift detector and digital pulse processor for the X-rays and a Timepix3 detector for the electrons. This setup enables recording time correlation between both event streams while at the same time preserving the complete conventional electron energy loss (EELS) and energy dispersive X-ray (EDX) signal. We show that the added coincidence information improves the sensitivity for detecting trace elements in a matrix as compared to conventional EELS and EDX. Furthermore, the method allows the determination of the collection efficiencies without the use of a reference sample and can subtract the background signal for EELS and EDX without any prior knowledge of the background shape and without pre-edge fitting region. We discuss limitations in time resolution arising due to specificities of the silicon drift detector and discuss ways to further improve this aspect.

Cathodoluminescence excitation spectroscopy: Nanoscale imaging of excitation pathways

“…2, A and B; and in the Supplementary Materials). Coincidence electron spectroscopy and microscopy have been performed in the past, for example, coincidence of EELS with secondary electron or x-ray emission (30)(31)(32). EELS-CL coincidence has been performed for discrete selected EELS energy ranges (33,34), but the relative QE as a function of energy and its spatial dependence has not been measured.…”

Cavity-mediated electron-photon pairs

“…From a broader perspective, harnessing correlations of electrons with radiative emission ( 34 ) shows promise for enhancing contrast and resolution, as recently shown in the study of core-level ( 35 ) and valence electronic excitations in nanostructured materials ( 36 ). Using postselection in the electronic and photonic degrees of freedom ( 9 , 13 ), such schemes can be generalized to trace state-specific scattering cross sections and create heralded pair states as a function of linear or angular momentum, polarization or spin, or frequency or energy.…”

Using a fast hybrid pixel detector for dose-efficient diffraction imaging beam-sensitive organic molecular thin films

“…In such a detector, single electron hits are registered by their location and time, forming a data stream of events. The interval of electron hit events could reach less than a couple of nanoseconds [31], making these detectors shine in cutting-edge applications such as coincidence spectroscopy [29,31,32] and the study of ultrafast phenomena [33]. For 4D-STEM applications, researchers have shown pixel dwell time down to ∼100 ns [29], thus a nominal frame speed of up to 10 MHz could be reached.…”