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A: Fachverband Atomphysik
A 18: Attosecond Physics II / Interaction with VUV and X-ray Light (joint session A/MO)
A 18.3: Vortrag
Mittwoch, 13. März 2024, 11:45–12:00, HS 1010
Extracting relative dipole moments from a laser-driven two-electron wave packet in helium by combining attosecond streaking and transient absorption spectroscopy — •Shuyuan Hu, Yu He, Gergana D. Borisova, Maximilian Hartmann, Paul Birk, Christian Ott, and Thomas Pfeifer — Max-Planck-Institut für Kernphysik, 69117 Heidelberg
The electronic structure of atoms and their interaction with light is reflected in complex-valued transition-matrix elements that have a magnitude and phase. In this work, a state-resolved phase of the time-delay dependent modulation of absorption is used to determine the relative signs of transition dipole matrix elements. This measurement relies on precise absolute calibration of the time-delay information, which is achieved by combining attosecond transient absorption and attosecond streaking spectroscopy to simultaneously measure the resonant photoabsorption spectra of laser-coupled doubly excited states in helium, together with the streaked photoelectron spectra. The streaking measurement reveals the absolute time delay zero and the full temporal profile of the interacting electric fields which is then used for a time-dependent few-level simulation of the relevant states. By comparing the 1-fs time-scale modulations across the 2s2p (1P) and sp2,3+ (1P) states between the time-delay calibrated simulation and measurement, we quantify the signs of the transition dipole matrix elements for the laser-coupled autoionizing states 2s2p-2p2 and 2p2-sp2,3+ to be opposite of each other.
Keywords: transition dipole matrix elements; XUV spectroscopy; streaking