Complete measurement experiments of the photoionization process were first carried out using synchrotron radiation. However,these experiments mostly focused on resonant photoionization processes and studies of inner-shell electrons,requiring consideration of spin-orbit coupling effects. Additionally,electron correlation effects such as Fano resonance,Auger decay,and fluorescence decay further complicate the physical processes,interfering with the accurate theoretical description.
Attosecond metrology techniques can acquire phase information of electron transitions,but the time delays caused by laser-Coulomb coupling effects or transitions from continuum to continuum increase the difficulty of measuring the intrinsic delay of light absorption.
In response to the limitations of existing experimental methods, Professor Jiang Yuhai's team proposed an innovative experimental scheme, developed the world's first rubidium cold-atom reaction microscope spectrometer, regulated magnetic quantum numbers using laser cooling technology, and obtained key information through the photoelectron momentum distribution (PMD) on the polarization plane. The experimental schematic diagram is shown in Figure 1. According to the tilt angle and interference structure in PMD, the relative amplitudes and phase shifts of ionization channels were successfully extracted, and the experimental results were in high agreement with the TDSE calculation results. A comprehensive characterization of the intermediate and final state wave functions was achieved, providing a benchmark complete measurement for the study of single-photon single ionization of hydrogen-like atoms.
This scheme has significant advantages: first,it does not depend on the ellipticity and intensity of the ionization laser,showing strong stability;second,compared with common pump-probe methods or inner-shell photoionization experiments,it effectively avoids the complexity of possible additional phase shifts or time delays,making the determination of phase and amplitude more direct. Looking to the future,this experimental method opens up new avenues for studying m-resolved transition dynamics of photoelectrons,circular dichroism,and resolving and controlling the interference between Zeeman sublevels on the attosecond time scale.
