Enhanced fragmentation of water dications upon high Rydberg states

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Chemical Physics

Background:

• Water ionization and fragmentation are crucial in many scientific fields.
• Relaxation pathways of water dications, especially the D+ + O+ + D channel, are not well understood.

Purpose of the Study:

• To investigate and elucidate the poorly understood fragmentation pathways of water dications.
• To identify and characterize novel fragmentation mechanisms induced by electron-impact.

Main Methods:

• Utilized multi-particle coincidence momentum spectroscopy.
• Employed electron-capture-mediated molecular dissociation calculations.
• Investigated electron-impact ionization and strong-field ionization experiments.

Main Results:

• Identified a Rydberg state-controlled fragmentation mechanism in water dications.
• Resolved the ultrafast relaxation dynamics of this fragmentation pathway (~2 fs).
• Demonstrated the occurrence of this mechanism in ammonia and laser-induced processes.

Conclusions:

• The study reveals a general molecular fragmentation pathway governed by high Rydberg states.
• This mechanism provides a molecular clock for probing electron-nuclear coupling.
• Offers new insights into the fundamental processes of water radiolysis.