Time-resolved photoemission on the attosecond scale: opportunities and challenges
Time-resolved photoemission on the attosecond scale: opportunities and challenges
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DOI：
10.1039/c3fd00004d
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发表时间：
2013-01-01
影响因子：
3.4
通讯作者：
Burgdoerfer, Joachim
中科院分区：
文献类型：
--
作者：
Pazourek, Renate;Nagele, Stefan;Burgdoerfer, Joachim
亚飞秒激光脉冲与物质的相互作用为在自然时间尺度上探索电子过程提供了机会。由在真实的时间中观察光电发射提出的一个中心概念问题是，光电子波包的喷射是否瞬时发生，或者对光吸收的响应时间是否是有限的，从而导致光电发射的时间延迟。最近的实验进展，探索阿秒条纹和RABBIT技术发现，从不同的原子亚态的光电发射之间的相对时间延迟的顺序是类似于20阿秒。我们提出了从头计算模拟的一个和两个电子系统，允许确定的绝对和相对时间延迟与类似的1阿秒精度。我们表明，编码在Eisenbud-Wigner-Smith延迟时间的光电离过程的固有时间偏移可以明确地从测量引起的时间延迟在泵浦探测设置时，光电离电子波包探测由一个适度强的红外条纹场。我们确定了初始态极化、最终连续态中的库仑激光耦合以及与纠缠剩余离子态的最终态相互作用所产生的不同贡献。扩展到多电子系统和提取的时间信息中存在的散肩过程进行了讨论。
The interaction of laser pulses of sub-femtosecond duration with matter opened up the opportunity to explore electronic processes on their natural time scale. One central conceptual question posed by the observation of photoemission in real time is whether the ejection of the photoelectron wavepacket occurs instantaneously, or whether the response time to photoabsorption is finite leading to a time delay in photoemission. Recent experimental progress exploring attosecond streaking and RABBIT techniques find relative time delays between the photoemission from different atomic substates to be of the order of similar to 20 attoseconds. We present ab initio simulations for both one-and two-electron systems which allow the determination of both absolute and relative time delays with similar to 1 attosecond precision. We show that the intrinsic time shift of the photoionization process encoded in the Eisenbud-Wigner-Smith delay time can be unambiguously disentangled from measurement-induced time delays in a pump-probe setting when the photoionized electronic wavepacket is probed by a modestly strong infrared streaking field. We identify distinct contributions due to initial-state polarization, Coulomb-laser coupling in the final continuum state as well as final-state interaction with the entangled residual ionic state. Extensions to multi-electron systems and to the extraction of time information in the presence of decohering processes are discussed.