Molecular fragmentation as a way to reveal early electron dynamics induced by attosecond pulses

Abstract

We present a theoretical study of the electron and nuclear dynamics that would arise in an attosecond two-color XUV-pump/XUV-probe experiment in glycine. In this scheme, the broadband pump pulse suddenly...

Attoscience in phase space

“…There is theoretical evidence that nuclear degrees of freedom in a large molecule weaken coherence. Still, it is remarkable that even in the worst-case scenario phase relations may survive [216]. The present review is a brief illustration of how phase space tools widely used in other research areas, such as quasiprobability densities, may be employed in attosecond physics.…”

“…Thereby, a key question is how to adapt these techniques to a highly transient, subfemtosecond regime, in the context of attochemistry. Recently, quantum and classical approaches have been combined to investigate electron and nuclear dynamics in pump-probe experiments in glycine, and the initial state was computed using phase space techniques [216]. Even in the single-electron regime, it is desirable to move from one-dimensional models.…”

“…Entanglement prevents coherent superpositions of states, which would lead to vibrational wave packets, from forming [219]. To be able to determine and prepare the ion in appropriate coherent superposition is really important in the context of attosecond hole migration [220,221] and pump-probe schemes [216,219,222], which rely on well-defined phase relationships. Electronic coherences also play a key role in XUV-induced bond formation [223].…”

“…This also implies that a density-matrix formalism and effective Hamiltonians [218,225], which are more suitable for open quantum systems, are required. This is particularly true if one takes into consideration the current trends, towards extended systems such as large molecules [216,[226][227][228][229][230] and nanostructures [231,232], for which overcoming decoherence, quantifying entanglement and nonclassical behaviour, and controlling the coupling with the environment will pose major challenges. There is theoretical evidence that nuclear degrees of freedom in a large molecule weaken coherence.…”

Controlling quantum effects in enhanced strong-field ionisation with machine-learning techniques

“…Recent studies using pump-probe schemes in H 2 have shown that coupling of electronic and vibrational degrees of freedom affects coherence and may hinder electron localisation [97]. Still, studies in large molecules indicate that phase relations may be preserved even in systems with many degrees of freedom [98], and could even be controlled leading to tailored ionisation enhancement or suppression [99]. Our simplified model is meant as a proof of concept and a first step towards more realistic scenarios.…”