# Spectroscopic coincidence experiments in transmission electron microscopy

## TL;DR

This paper demonstrates a novel coincidence measurement technique in transmission electron microscopy that correlates EELS and EDX events, significantly improving elemental detection sensitivity and background suppression without relying on traditional background fitting methods.

## Contribution

It introduces a method using a delay line detector for real-time coincidence measurements in TEM, enhancing elemental analysis by reducing background noise.

## Key findings

- Coincidence measurements reveal atomic excitation and de-excitation correlations.
- The method significantly suppresses background in EELS spectra.
- It enables detection of low-concentration elements in complex matrices.

## Abstract

We demonstrate the feasibility of coincidence measurements in a conventional transmission electron microscope, revealing the temporal correlation between electron energy loss spectroscopy (EELS) and energy dispersive X-ray (EDX) spectroscopy events. We make use of a delay line detector with picosecond time resolution attached to a modified EELS spectrometer. We demonstrate that coincidence between both events, related to the excitation and de-excitation of atoms in a crystal, provides added information not present in the individual EELS or EDX spectra. In particular, the method provides EELS with a significantly suppressed or even removed background, overcoming the many difficulties with conventional parametric background fitting as it uses no assumptions on the shape of the background, requires no user input and does not suffer from counting noise originating from the background signal. This is highly attractive, especially when low concentrations of elements need to be detected in a matrix of other elements.