Dissociative electron attachments to ethanol and acetaldehyde: A combined experimental and simulation study

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Dynamics

Background:

• Understanding the dissociation dynamics of molecules after electron attachment is crucial for chemical reaction mechanisms.
• Temporary negative ions play a significant role in electron-molecule interactions and subsequent fragmentation processes.

Purpose of the Study:

• To investigate the dissociation dynamics of ethanol and acetaldehyde following low-energy electron attachment.
• To elucidate the fragmentation pathways and kinetic energy distributions of resulting ions.

Main Methods:

• Utilizing the anion velocity map imaging technique to capture fragment ion momentum.
• Employing ab initio molecular dynamics simulations to model and understand fragmentation processes.

Main Results:

• Observed distinct kinetic energy distributions for O(-)/OH(-) fragments from ethanol and O(-) fragments from acetaldehyde.
• Recorded low kinetic energies for O(-)/OH(-) from ethanol and both low and high kinetic energies for O(-) from acetaldehyde.
• Identified low kinetic energy for CH3(-) fragments from acetaldehyde.

Conclusions:

• Proposed a novel cascade dissociation pathway for slow O(-) ion production in ethanol via a dehydrogenated intermediate.
• Clarified the rapid two-body dissociation and internal energy redistribution leading to slow CH3(-) formation in acetaldehyde after electron attachment.