Formaldehyde roaming dynamics: Comparison of quasi-classical trajectory calculations and experiments

Area of Science:

• Chemical Physics
• Molecular Dynamics
• Spectroscopy

Background:

• Formaldehyde photodissociation is a key process in atmospheric chemistry.
• Understanding dissociation pathways, including roaming, is crucial for accurate chemical modeling.
• Previous potential energy surfaces (PES) limited detailed dynamical studies.

Purpose of the Study:

• To investigate the photodissociation dynamics of formaldehyde using a new potential energy surface (PES).
• To compare quasi-classical trajectory calculations with detailed experimental results for CO + H2 product distributions.
• To elucidate correlations between internal states of CO and H2 products from roaming and transition-state pathways.

Main Methods:

• Quasi-classical trajectory (QCT) calculations on a newly developed PES.
• Detailed experimental measurements of CO and H2 product state distributions.
• Analysis of correlations between vibrational/rotational states and speed distributions of dissociation products.

Main Results:

• The new PES significantly improves the accuracy of photodissociation dynamics simulations.
• Satisfactory agreement between QCT calculations and experimental data for product state distributions.
• Detailed correlations between CO and H2 internal states were revealed for both roaming and transition-state pathways.

Conclusions:

• The new PES and experimental techniques are valuable for studying formaldehyde photodissociation.
• The findings support the detailed understanding of roaming dynamics in molecular dissociation.
• This work provides a foundation for future investigations into photodissociative processes.