Timing of charge migration in betaine by impact of fast atomic ions

Abstract

The way molecules break after ion bombardment is intimately related to the early electron dynamics generated in the system, in particular, charge (or electron) migration. We exploit the natural positive-negative charge splitting in the zwitterionic molecule betaine to selectively induce double electron removal from its negatively charged side by impact of fast O 6+ ions. The loss of two electrons in this localized region of the molecular skeleton triggers a competition between direct Coulomb explosion and charge migration that is examined to obtain temporal information from ion-ion coincident measurements and nonadiabatic molecular dynamics calculations. We find a charge migration time, from one end of the molecule to the other, of approximately 20 to 40 femtoseconds. This migration time is longer than that observed in molecules irradiated by ultrashort light pulses and is the consequence of charge migration being driven by adiabatic nuclear dynamics in the ground state of the molecular dication.

Photofragmentation specificity of photoionized cyclic amino acids (diketopiperazines) as precursors of peptide building blocks

“…faces. This strategy has been previously employed with success for ionized molecules and molecular clusters [4][5][6]10,[37][38][39][40][41][42][43][44][45] . Ab initio molecular dynamics allow following the fragmentation pathways for the first hundreds of femtoseconds after ionisation.…”

“…This strategy has been previously employed with success for ionized molecules and molecular clusters. [4][5][6]10,[37][38][39][40][41][42][43][44][45] Ab initio molecular dynamics allow following the fragmentation pathways for the first hundreds of femtoseconds after ionisation. We have used the atom-centred density matrix propagation (ADMP) formalism [46][47][48] at the DFT level of theory, in particular using the B3LYP functional [49][50][51][52] with the 6-31++G(d,p) basis set.…”

Ultrafast Roaming Mechanisms in Ethanol Probed by Intense Extreme Ultraviolet Free-Electron Laser Radiation: Electron Transfer versus Proton Transfer

“…Charge transfer, charge migration, and charge separation between the atomic centers of a molecule are crucial steps in chemical bond formation and dissociation and also play an important role in internal conversion. − When triggered by photoabsorption or particle impact, the change in the molecular electronic structure induces nuclear motion, which can result in substantial changes in molecular geometry, e.g., isomerization − and dissociation . Additionally, the ultrafast charge/hole transfer has an important impact on radiation damage in biological systems, e.g., the DNA mutations induced by proton transfer (PT) .…”