Reaction Pathways of Water Dimer Following Single Ionization

Area of Science:

• Atmospheric Chemistry
• Physical Chemistry
• Spectroscopy

Background:

• Water dimer (H2O)2 is a key hydrogen-bonded system in Earth's atmosphere.
• It serves as a model for understanding proton transfer and ionic dynamics in chemical and biochemical processes.
• Studying water dimer provides insights into astro- and atmospheric chemistry.

Purpose of the Study:

• To investigate the fragmentation pathways of ionized water dimer ((H2O)2+) after single ionization.
• To identify and characterize all resulting ion products and their yields.
• To present detailed reaction energetics for fragmentation pathways, including novel ones.

Main Methods:

• Utilized a purified molecular beam of water dimer.
• Employed multimass ion imaging techniques for simultaneous detection of all ion products.
• Analyzed ion yields and fragmentation energetics.

Main Results:

• Successfully detected all ion products from (H2O)2+ fragmentation.
• Identified 13 ion-radical pathways, with 6 previously unreported.
• Presented detailed data on ion yields and reaction energetics for these pathways.
• Observed significant 18O-isotope effects, providing further mechanistic insights.

Conclusions:

• The study comprehensively maps the fragmentation landscape of ionized water dimer.
• New insights into hydrogen bonding and atmospheric water cluster chemistry are provided.
• The findings contribute to a deeper understanding of fundamental processes in atmospheric and astrochemistry.