Spatiotemporal analysis of a final-state shape resonance in interferometric photoemission from Cu(111) surfaces
Spatiotemporal analysis of a final-state shape resonance in interferometric photoemission from Cu(111) surfaces
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DOI：
10.1103/physreva.100.043412
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发表时间：
2019-10-21
影响因子：
2.9
通讯作者：
Thumm, U.
中科院分区：
文献类型：
--
作者：
Ambrosio, M. J.;Thumm, U.
固体靶的光发射包括基板内电子的激发和运动，然后是它们在真空中的传播和检测。因此，它取决于固体在束缚初始态和连续体最终态两个不同谱域中的电子能带结构。虽然在能域的标准光电子能谱中常规检查固体的静态（初始态）价电子结构在光电子能谱上的印记，但最先进的时间分辨光电子能谱还可以检查电子连续体中的光电子传播。在固体阿秒时间分辨干涉光电子发射的量子力学模型中，我们计算了光发射光谱作为激发主阿秒脉冲串和辅助红外（IR）激光脉冲之间延迟的函数。考虑到光电子与红外激光电场和周期性基底的终态相互作用，我们对 Cu(111) 表面 3d 价带干涉光发射的数值结果显示，在光电子动能接近 24 eV 时，边带产额显着共振增强，同时固体内部的光电子波函数振幅在几纳米的长度尺度上显着增加。最终态光电子概率密度向体的共振偏移可以解释为固体中光电子传播时间的增加，并且与 Kasmi 等人在最近的双路双光子干涉光谱中观察到的共振增强光谱边带相移相称。 [光学 4, 1492 (2017)]。
Photoemission from solid targets includes the excitation and motion of electrons inside the substrate, followed by their propagation in vacuum and detection. It thus depends on the electronic band structure of the solid in the two distinct spectral domains of bound initial and continuum final states. While the imprint of the static (initial-state) valence electronic structure of solids on photoemission spectra is routinely examined in standard photoemission spectroscopy in the energy domain, state-of-the-art time-resolved photoelectron spectroscopy allows, in addition, the scrutiny of photoelectron propagation in the electronic continuum. Within a quantum-mechanical model for attosecond time-resolved interferometric photoelectron emission from solids, we calculated photoemission spectra as a function of the delay between the exciting primary attosecond pulse train and assisting infrared (IR) laser pulse. Accounting for final-state interactions of the photoelectron with the IR laser electric field and the periodic substrate, our numerical results for interferometric photoemission from the 3d-valence band of Cu(111) surfaces show a striking resonantly enhanced sideband yield at photoelectron kinetic energies near 24 eV, in conjunction with a pronounced increase of the photoelectron wave-function amplitude inside the solid on a length scale of a few nanometers. This resonant shift of final-state photoelectron-probability density towards the bulk can be interpreted as an increase in the photoelectron propagation time in the solid and is commensurate with the resonantly enhanced spectral sideband-phase shifts observed in recent two-pathway two-photon interference spectra by Kasmi et al. [Optica 4, 1492 (2017)].