  The coupling of electronic and nuclear motion in polyatomic molecules is at
the heart of attochemistry. The molecular properties, transient structures and
reaction mechanism of these many-body quantum objects are defined on the level
of electrons and ions by molecular wave functions and their coherent
superposition, respectively. In the present contribution we monitor
nonadiabatic quantum wave packet dynamics during molecular charge motion by
reconstructing both, the oscillatory charge density distribution and the
characteristic time-dependent nuclear configuration coordinate from
time-resolved Auger electron spectroscopic data recorded in previous studies on
glycine molecules [Sci. Adv. 2022, 8, eabn6848]. The electronic and nuclear
motion on the femtosecond timescale was induced and probed in kinematically
complete soft x-ray experiments at the FLASH free-electron laser facility. The
detailed analysis of amplitude, instantaneous phase and instantaneous frequency
of the propagating many-body wave packet during its lifecycle provides
unprecedented insight into dynamical processes beyond the Born-Oppenheimer
approximation. We are confident that the refined experimental data evaluation
helps to develop new theoretical tools to describe time-dependent molecular
wave functions in complicated, but ubiquitous, non-Born-Oppenheimer
photochemical conditions.
