RABBITT with tailored fields: Measuring dipole transitions in the continuum

具有定制场的 RABBITT：测量连续介质中的偶极子跃迁

• 批准号: 411044455
• 负责人: Dr. Anne Harth
• 金额: --
• 依托单位: Max-Planck-Institut für Kernphysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/411044455?language=en
• 关键词: RABBITT; tailored; elds; Measuring; dipole

Attosecond pulses allow the observation of attosecond dynamics of electron motion in a variety of different systems. One method to measure such ultrafast dynamics is based on the reconstruction of attosecond beating by the interference of two-photon transitions (also called RABBITT). As the name suggests, the RABBITT method is based on two-photon transition steps: a train of attosecond pulses ionizes the system, this is the first photo absorption step, and a weak probe field drives a continuum-continuum dipole transition. In this project we propose an experiment, based on an extended RABBITT technique, promising to gain general information about dipole transitions in the continuum. The main idea is to compare two RABBITT measurements, where the ionization step is the same for both measurements, but e.g. the number of continuum-continuum transitions differ. This can be realized choosing a smaller probe frequency.When e.g. the attosecond pulse train is generated by a driving laser with a frequency of 2ω, the standard RABBITT method uses the same frequency 2ω as probe beam. But if the half frequency ω will be used, two continuum-continuum transitions are involved. This multi-color Rabbit method is easily extendable generating the attosecond pulse train e.g. with the third harmonic and probe the system with the third or second or fundamental field. It will be also possible to probe with a multi-color field, when e.g. the second and fundamental fields are mixed. These tailored fields can be further manipulated by changing the phase or the polarization of one of the fields. The knowledge gained with the multi-color RABBITT technique is important for the correct interpretation of experiments dealing with attosecond dynamics close to the ionization threshold.

阿秒脉冲允许在各种不同的系统中观察电子运动的阿秒动力学。测量这种超快动力学的一种方法是基于通过双光子跃迁干涉重建阿秒拍频（也称为RABBITT）。顾名思义，RABBITT方法基于双光子跃迁步骤：一系列阿秒脉冲电离系统，这是第一个光吸收步骤，弱探测场驱动连续-连续偶极跃迁。在这个项目中，我们提出了一个实验，扩展的RABBITT技术的基础上，有望获得有关偶极跃迁的连续谱的一般信息。主要思想是比较两个RABBITT测量，其中两个测量的电离步骤是相同的，但是例如连续-连续跃迁的数量不同。例如，当阿秒脉冲串由频率为2ω的驱动激光器产生时，标准的RABBITT方法使用相同的频率2ω作为探测光束。但如果使用半频ω，则涉及两个连续-连续跃迁。这种多色兔子方法很容易扩展，例如用三次谐波产生阿秒脉冲串，并用三次或二次或基波探测系统。当第二场和基本场混合时，也可以使用多色场进行探测。这些定制的场可以通过改变其中一个场的相位或偏振来进一步操纵。用多色RABBITT技术获得的知识对于正确解释接近电离阈值的阿秒动力学实验是重要的。