Concerted Double Hydrogen-Bond Breaking by Intermolecular Coulombic Decay in the Formic Acid Dimer.

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Dynamics

Background:

• Hydrogen bonds are crucial for condensed phase molecular systems.
• Understanding excited-state dynamics of hydrogen-bonded complexes is incomplete.

Purpose of the Study:

• Investigate ultrafast decay processes in formic acid dimers after electron removal.
• Elucidate the role of nonlocal decay in hydrogen bond dynamics.

Main Methods:

• Utilized electron-beam irradiation and fragment-ion/electron coincident momentum measurements.
• Performed ab initio calculations for theoretical analysis.

Main Results:

• Observed ultrafast energy transfer between formic acid molecules initiated by inner-valence electron removal.
• Identified nonlocal decay leading to ionization and low-energy electron emission.
• Revealed concerted double hydrogen bond breaking driven by cation rotation.

Conclusions:

• The study uncovers a novel nonlocal decay mechanism in formic acid dimers.
• Demonstrates ultrafast dynamics and bond breaking initiated by electronic excitation.