Investigation of the continuum-continuum phase in attosecond time delays

阿秒时滞中连续相-连续相的研究

• 批准号: 493861873
• 负责人: Professor Dr. Giuseppe Sansone
• 金额: --
• 依托单位: Department of Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/493861873?language=en
• 关键词: Investigation; continuum; phase; attosecond; time

The process of photoionisation has been assumed for a long time to be an instantaneous process: a photon of sufficient energy impinges on a quantum system (atom, molecule or surface) and an electron is instantaneously released in the continnum. The development of attosecond technologies has allowed, for the first time, to resolve in time this fundamental process and to measure time delays between the photoelectrons emitted from different energy levels in the same system or from different quantum systems. The measurement of these delay is relevant, as it gives access to the characteristics of the potential experienced by the electrons on its way out. All experiment focused on the characterization of time delays are based on the combination of an attosecond waveform in the extreme ultraviolet and (typically) an infrared laser pulse. The interaction with the latter introduces an additional delay (indicated as continuum-continuum (CC) delay), which must be corrected for, in order to isolate the response of the quantum system to the attosecond field. The estimation of the CC delay has been based so far on theoretical models and no experimental measurement has been reported so far. The goal of this project is to provide the first experimental characterization of the CC delay, by taking advantage of the results recently demonstrated at the Free-Electron Laser FERMI by the proponent. The project will be based on the development on an optical parametric amplifier that, combined with an attosecond train source, will give the possibility to generate photoelectron spectra encoding directly the information on the CC delay. The results will be compared with numerical solution of the TDSE and predictions of perturbation theory that will be delivered by two theoretical groups supporting the project.

长期以来，光电离的过程一直被认为是一个瞬时过程：一个足够能量的光子撞击一个量子系统（原子、分子或表面），一个电子在连续体中瞬间释放。阿秒技术的发展首次允许及时解决这一基本过程，并测量从同一系统或不同量子系统中的不同能级发射的光电子之间的时间延迟。这些延迟的测量是相关的，因为它可以获得电子在离开时所经历的电势的特性。 所有的实验都集中在表征时间延迟的基础上的阿秒波形在极紫外和（通常）红外激光脉冲的组合。与后者的相互作用引入了额外的延迟（表示为连续-连续（CC）延迟），必须对其进行校正，以隔离量子系统对阿秒场的响应。到目前为止，CC延迟的估计是基于理论模型的，并且到目前为止还没有实验测量的报道。该项目的目标是提供CC延迟的第一个实验表征，通过利用最近在自由电子激光器FERMI的支持者证明的结果。该项目将基于光学参量放大器的发展，结合阿秒列车源，将产生直接编码CC延迟信息的光电子谱的可能性。结果将与数值解的TDSE和微扰理论的预测，将提供两个理论组支持该项目进行比较。