Subthermal Mean Transverse Energies Induced by Electron Refraction on the Jump in Mass at the Surface of Multialkali Photocathodes

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Auteurs principaux: Rozhkov, S. A., Bakin, V. V., Scheibler, H. E., Rusetsky, V. S., Gorshkov, D. V., Kustov, D. A., Golyashov, V. A., Alperovich, V. L., Tereshchenko, O. E.
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Publié: 2025
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author Rozhkov, S. A.
Bakin, V. V.
Scheibler, H. E.
Rusetsky, V. S.
Gorshkov, D. V.
Kustov, D. A.
Golyashov, V. A.
Alperovich, V. L.
Tereshchenko, O. E.
author_facet Rozhkov, S. A.
Bakin, V. V.
Scheibler, H. E.
Rusetsky, V. S.
Gorshkov, D. V.
Kustov, D. A.
Golyashov, V. A.
Alperovich, V. L.
Tereshchenko, O. E.
contents The search for photocathode materials with low mean transverse energies (MTEs) and, hence, low intrinsic emittance is of crucial importance for various fields of particle and solid state physics. Here, we demonstrate that polycrystalline multialkali Na$_{2}$KSb(Cs,Sb) photocathodes with negative effective electron affinity (NEA) have MTE values at room temperature by a factor of 2 lower than those of monocrystalline \textit{p}-GaAs(Cs,O) photocathodes. These low MTE values are due to the electron refraction on the jump in mass, between a small effective mass in Na$_{2}$KSb and free electron mass in vacuum. It is proved that, at the NEA state, up to half of photoelectrons are emitted in a narrow-angle cone with the fractional MTE of 9\,meV at room temperature. We also showed that the transition from NEA to positive effective affinity results in the subthermal total MTE of the Na$_{2}$KSb(Cs,Sb) photocathode, along with quantum efficiency of about 10$^{-2}$. The physical reasons for the manifestation of the refraction effect in multialkali photocathodes are discussed, opening up opportunities for the development of high-brightness and ultracold robust electron sources.
format Preprint
id arxiv_https___arxiv_org_abs_2510_02897
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Subthermal Mean Transverse Energies Induced by Electron Refraction on the Jump in Mass at the Surface of Multialkali Photocathodes
Rozhkov, S. A.
Bakin, V. V.
Scheibler, H. E.
Rusetsky, V. S.
Gorshkov, D. V.
Kustov, D. A.
Golyashov, V. A.
Alperovich, V. L.
Tereshchenko, O. E.
Materials Science
The search for photocathode materials with low mean transverse energies (MTEs) and, hence, low intrinsic emittance is of crucial importance for various fields of particle and solid state physics. Here, we demonstrate that polycrystalline multialkali Na$_{2}$KSb(Cs,Sb) photocathodes with negative effective electron affinity (NEA) have MTE values at room temperature by a factor of 2 lower than those of monocrystalline \textit{p}-GaAs(Cs,O) photocathodes. These low MTE values are due to the electron refraction on the jump in mass, between a small effective mass in Na$_{2}$KSb and free electron mass in vacuum. It is proved that, at the NEA state, up to half of photoelectrons are emitted in a narrow-angle cone with the fractional MTE of 9\,meV at room temperature. We also showed that the transition from NEA to positive effective affinity results in the subthermal total MTE of the Na$_{2}$KSb(Cs,Sb) photocathode, along with quantum efficiency of about 10$^{-2}$. The physical reasons for the manifestation of the refraction effect in multialkali photocathodes are discussed, opening up opportunities for the development of high-brightness and ultracold robust electron sources.
title Subthermal Mean Transverse Energies Induced by Electron Refraction on the Jump in Mass at the Surface of Multialkali Photocathodes
topic Materials Science
url https://arxiv.org/abs/2510.02897