Future challenges: general discussion

Onset of ionic coherence and ultrafast charge dynamics in attosecond molecular ionisation

“…Tel: 0044 20 7589 47728; E-mail: m.ruberti11@imperial.ac.uk using both table-top high harmonic generation (HHG) [30][31][32][33][34][35][36] and free-electron laser (FEL) sources [37][38][39][40][41][42][43] , that would open the way to attosecond pump-attosecond probe experiments. Following this rapid progress 44,45 , several time-resolved spectroscopic techniques have been developed 18,19,[46][47][48][49][50][51][52][53][54][55] and have demonstrated unprecedented temporal resolution 14,57,58 in real-time tracing of both valence and core coherent electron dynamics as well as nuclear motion 56 . In particular, first experimental evidence of pure electronic, few-fs, charge oscillations after ionisation of the phenylalanine molecule 18 and the iodoacetylene molecule 19 were recently reported.…”

Restricted Correlation Space B-Spline ADC Approach to Molecular Ionization: Theory and Applications to Total Photoionization Cross-Sections

“…Over the past few decades, the groundbreaking development of ultrashort laser pulses in a broad range of the electromagnetic spectrum, from near-infrared femtosecond pulses to extreme ultraviolet (XUV) and X-ray attosecond ones, has enabled the experimental study of electron dynamics in atoms and molecules on its natural time scale, − giving one a direct insight into how electronic rearrangement may affect chemical properties. − Considerable effort has been made to produce controlled intense few-cycle XUV and X-ray laser pulses, using both table-top high harmonic generation (HHG) − and free-electron laser (FEL) sources. , In particular, the spectacular experimental progress in incorporating attosecond technology in FEL, − in order to generate intense ultrashort XUV pulses with high spatial and temporal coherence, and extending the HHG technology to reach the water window (3–4 nm wavelength), − has opened the way to attosecond pump–probe experiments ,,,− and the study of ultrafast correlated many-electron dynamics both in the valence and core energy regions.…”

Full Ab Initio Many-Electron Simulation of Attosecond Molecular Pump–Probe Spectroscopy

“…10 Another promising scheme for real-time tracking of impulsively created valence electronic wavepackets and electronic coherences has been suggested, based on nonlinear X-ray spectroscopy. 11 Such schemes have a proven potential for capturing both purely bound (e.g., hole migration 8,10 ), and bound-continuum (e.g., Auger decay 12,13 ) many-electron dynamics in molecules on their intrinsic time scales. However, the outcomes of such molecular pump−probe experiments are often notoriously difficult to interpret unambiguously, because of the richness of the dynamics encoded in the data.…”

“…Spectacular experimental progress has also been made on the hybrid schemes involving both attosecond and few-femtosecond IR pulses, such as those based on transient absorption, , high-harmonic generation (HHG) spectroscopy, , and XUV/VUV-IR pump–probe . Another promising scheme for real-time tracking of impulsively created valence electronic wavepackets and electronic coherences has been suggested, based on nonlinear X-ray spectroscopy . Such schemes have a proven potential for capturing both purely bound (e.g., hole migration , ), and bound-continuum (e.g., Auger decay , ) many-electron dynamics in molecules on their intrinsic time scales.…”