Electron Pair Emission Spectroscopy in Solid Materials

Electron pair emission spectroscopy probes the simultaneous emission of two electrons from a solid following interaction with photons or primary electrons. By measuring the kinetic energies and emission angles of both electrons in coincidence, this technique reveals correlated electronic processes within the material. Sum‐energy spectra and angular distributions provide direct insight into many‐body interactions, exchange and correlation holes, and the dynamics of core‐hole decay. Advances in instrumentation now enable six‐dimensional data collection—tracking two energies and four angular coordinates per event—while ultrafast light sources allow attosecond‐scale resolution of core‐hole lifetimes. Applications span the characterisation of metal and semiconductor surfaces, investigation of quantum‐confined systems, and mapping of ultrafast electron transfer in catalysts and nanostructures. By uncovering fundamental electron–electron interactions and transient states, electron pair emission spectroscopy informs the design of novel materials for electronics, photonics and energy conversion.

Research from Nature Portfolio

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Research from all publishers

Recent work has demonstrated a novel double resonant Raman decay pathway in silver surfaces, where two 4p core holes are excited near threshold. Analysis of two‐dimensional kinetic energy maps revealed a diagonal feature whose width corresponds to a 30‐attosecond core‐hole lifetime, while the linear dispersion of the energy sum with photon energy identifies an unexpected Raman‐like emission channel. Another study applied coincidence spectroscopy to copper surfaces using circularly polarised light, showing that the handedness of incident photons is encoded in the emitted electron pair. Dichroism signals observed for both core‐level and valence‐band emission pathways confirm that the pair obeys chiral selection rules, shedding light on single‐step Auger decay and opening routes to spin‐ and symmetry‐resolved surface analysis. Foundational experiments with a dedicated coincidence station at a synchrotron facility have delivered six‐dimensional datasets for silver surfaces, separating contributions from different core‐level transitions and extracting two‐hole state energy distributions. These developments illustrate the growing ability to resolve multi‐electron dynamics with high resolution and selectivity, driving forward both fundamental studies and applied surface science.

Electron Pair Emission Spectroscopy in Solid Materials publication trend

The graph below shows the total number of articles in electron pair emission spectroscopy in solid materials across all publications each year (not limited to Nature Index journals).

Technical terms

Electron pair emission spectroscopy: A technique that detects two emitted electrons in coincidence to study correlated electronic processes in solids.

Coincidence spectroscopy: Measurement of two or more particles emitted from the same excitation event, allowing correlation of their energies and angles.

Auger electron: An electron emitted when an inner‐shell vacancy is filled by an outer‐shell electron, with the excess energy transferred to a second electron.

Photoelectron: An electron ejected from a material by absorption of a photon.

Core hole: A vacancy left in an inner electronic shell after photoionisation or other excitation.

Fermi level: The highest occupied electronic energy level at absolute zero temperature in a solid.

Work function: The minimum energy required to remove an electron from the Fermi level of a solid into vacuum.

References

1. The CoESCA station at BESSY: Auger electron–photoelectron coincidences from surfaces demonstrated for Ag MNN. Journal of Electron Spectroscopy and Related Phenomena (2021).
2. Chirality in double photoemission from a Cu(100) surface. Journal of Vacuum Science & Technology A Vacuum Surfaces and Films (2022).
3. Evidence for double resonant Raman decay from a Ag surface. Physical Review B (2024).