TY - JOUR
T1 - Ultracold Electrons via Near-Threshold Photoemission from Single-Crystal Cu(100)
AU - Karkare, Siddharth
AU - Adhikari, Gowri
AU - Schroeder, W. Andreas
AU - Nangoi, J. Kevin
AU - Arias, Tomas
AU - Maxson, Jared
AU - Padmore, Howard
N1 - Publisher Copyright:
© 2020 American Physical Society.
PY - 2020/7/31
Y1 - 2020/7/31
N2 - Achieving a low mean transverse energy or temperature of electrons emitted from the photocathode-based electron sources is critical to the development of next-generation and compact X-ray free electron lasers and ultrafast electron diffraction, spectroscopy, and microscopy experiments. In this Letter, we demonstrate a record low mean transverse energy of 5 meV from the cryo-cooled (100) surface of copper using near-threshold photoemission. Further, we also show that the electron energy spread obtained from such a surface is less than 11.5 meV, making it the smallest energy spread electron source known to date: More than an order of magnitude smaller than any existing photoemission, field emission, or thermionic emission based electron source. Our measurements also shed light on the physics of electron emission and show how the energy spread at few meV scale energies is limited by both the temperature and the vacuum density of states.
AB - Achieving a low mean transverse energy or temperature of electrons emitted from the photocathode-based electron sources is critical to the development of next-generation and compact X-ray free electron lasers and ultrafast electron diffraction, spectroscopy, and microscopy experiments. In this Letter, we demonstrate a record low mean transverse energy of 5 meV from the cryo-cooled (100) surface of copper using near-threshold photoemission. Further, we also show that the electron energy spread obtained from such a surface is less than 11.5 meV, making it the smallest energy spread electron source known to date: More than an order of magnitude smaller than any existing photoemission, field emission, or thermionic emission based electron source. Our measurements also shed light on the physics of electron emission and show how the energy spread at few meV scale energies is limited by both the temperature and the vacuum density of states.
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U2 - 10.1103/PhysRevLett.125.054801
DO - 10.1103/PhysRevLett.125.054801
M3 - Article
C2 - 32794833
AN - SCOPUS:85089478256
SN - 0031-9007
VL - 125
JO - Physical Review Letters
JF - Physical Review Letters
IS - 5
M1 - 054801
ER -