Wave packet interferometry provides benchmark information on light-induced electronic quantum states by monitoring their relative amplitudes and phases during coherent excitation, propagation, and decay. The relative phase control of soft x-ray pulse replicas on the single-digit attosecond timescale achieved in our experiments makes this method a powerful tool to probe ultrafast quantum phenomena such as the excitation of Auger shake-up states with sub-cycle precision. In this contribution we present first results obtained for different Auger decay channels upon generating L-shell vacancies in argon atoms using Michelson-type all-reflective interferometric autocorrelation at a central free-electron laser photon energy of 274.7eV.

波包干涉测量法通过监测相干激发，传播和衰减期间的相对振幅和相位，提供有关光诱导电子量子态的基准信息。在我们的实验中，在一位数的阿秒级时间尺度上对软X射线脉冲副本的相对相位控制使该方法成为探测超快速量子现象（如具有亚循环精度的俄歇振动状态激发）的有力工具。在这项贡献中，我们介绍了在中心自由电子激光光子能量为274.7eV时，使用迈克尔逊型全反射干涉自相关技术在氩原子中产生L壳空位时在不同的俄歇衰变通道上获得的第一个结果。