Roaming in acetaldehyde

Area of Science:

• Chemical Dynamics
• Photochemistry
• Molecular Spectroscopy

Background:

• Roaming dynamics in molecular photodissociation are crucial for understanding reaction pathways.
• Acetaldehyde (CH3CHO) and formaldehyde (H2CO) exhibit distinct photochemical behaviors.

Purpose of the Study:

• To investigate and differentiate roaming dynamics in acetaldehyde photodissociation.
• To compare acetaldehyde's roaming mechanisms with those of formaldehyde.

Main Methods:

• Full-dimensional trajectory studies on acetaldehyde.
• Analysis using a two-degree-of-freedom restricted model.
• Phase space analysis to assess pathway accessibility.

Main Results:

• Evidence for two distinct roaming pathways in acetaldehyde photodissociation.
• Roaming observed at shorter (9-11.5 au) and larger (14.5-22.9 au) CH3-HCO separations.
• Shorter-range roaming is unique to acetaldehyde, involving repulsive interactions.

Conclusions:

• Acetaldehyde exhibits multiple roaming mechanisms, contributing to its increased roaming propensity.
• A restricted model accurately reproduces longer-range roaming, analogous to formaldehyde.
• Shorter-range roaming in acetaldehyde is facilitated by factors absent in simplified models.