Brightness of femtosecond nonequilibrium photoemission in metallic photocathodes at wavelengths near the photoemission threshold

被引：16

作者：

Bae, Jai Kwan ^{[1
]}

Bazarov, Ivan ^{[1
]}

Musumeci, Pietro ^{[2
]}

Karkare, Siddharth ^{[3
]}

Padmore, Howard ^{[4
]}

Maxson, Jared ^{[1
]}

机构：

[1] Cornell Univ, Cornell Lab Accelerator Based Sci & Educ, Ithaca, NY 14853 USA

[2] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA

[3] Arizona State Univ, Dept Phys, Tempe, AZ 85287 USA

[4] LBNL, Adv Light Source Div, Berkeley, CA 94720 USA

来源：

JOURNAL OF APPLIED PHYSICS | 2018年 / 124卷 / 24期

基金：

美国国家科学基金会;

关键词：

ELECTRON DYNAMICS;

D O I：

10.1063/1.5053082

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

The operation of photoemission electron sources with wavelengths near the photoemission threshold has been shown to dramatically decrease the minimum achievable photocathode emittance, but at the cost of significantly reduced quantum efficiency (QE). In this work, we show that for femtosecond laser and electron pulses, the increase in required laser intensities due to the low QE drives the photocathode electronic distribution far from static equilibrium. We adapt an existing dynamic model of the electron occupation under high intensity laser illumination to predict the time-dependent effects of the nonequilibrium electron distribution on the QE, mean transverse energy (MTE), and emission brightness of metal photocathodes. We find that multiphoton photoemission dramatically alters the MTE as compared to thermal equilibrium models, causing the MTE to no longer be a monotonic function of photon excess energy. Published by AIP Publishing.

引用

页数：6

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