Near-Threshold Photoemission from Graphene-Coated Cu (110)

Christopher J. Knill, Hisato Yamaguchi, Kenji Kawahara, Gaoxue Wang, Enrique Batista, Ping Yang, Hiroki Ago, Nathan Moody, Siddharth Karkare

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


The brightness of electron beams emitted from photocathode sources plays a critical role in determining the performance of x-ray free-electron lasers and ultrafast electron-diffraction applications. In order to achieve the maximum brightness, the electrons need to be emitted from a photocathode with the lowest-possible mean transverse energy (MTE). Recent investigations have shown that capping a Cu(110) photocathode with a monolayer of graphene can protect the quantum efficiency (QE) from long-term exposure to varying vacuum conditions. However, there have been no studies that investigate the effects that a monolayer of graphene has on the MTE. Here, we report on measurements of a graphene-coated Cu(110) single crystal near the photoemission threshold for room and liquid-nitrogen temperatures. At room temperature, a minimum MTE of 25 meV is measured at 295 nm. At liquid-nitrogen temperatures, a minimum MTE of 9 meV is measured at the photoemission threshold of 290 nm.

Original languageEnglish
Article number014015
JournalPhysical Review Applied
Issue number1
Publication statusPublished - Jan 2023

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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