Photodissociation dynamics of SOCl2

Area of Science:

• Chemical Physics
• Photochemistry
• Molecular Dynamics

Background:

• Thionyl chloride (SOCl2) photodissociation is crucial for understanding chemical reaction pathways.
• Previous studies have provided fragmented data on SOCl2 dissociation dynamics.

Purpose of the Study:

• To unify existing and new data on SOCl2 ultraviolet photodissociation.
• To elucidate the competing dissociation channels and their dynamics.

Main Methods:

• Time-dependent density functional theory (TD-DFT) with B3LYP functional for excitation energies.
• 3D photofragment imaging using resonance-enhanced multi-photon ionization (REMPI) and time-of-flight (TOF).
• Analysis of fragment speed distributions and anisotropy parameters.

Main Results:

• Observed atomic chlorine fragments in ground [Cl] and excited [Cl*] states.
• Identified bimodal speed distributions indicating competition between radical and three-body decay.
• Found no evidence for molecular fragmentation into SO + Cl2.
• Observed increasing anisotropy with fragment speed, suggesting different excited state involvement.

Conclusions:

• The study provides a unified interpretation of SOCl2 photodissociation.
• Simultaneous excitation of multiple electronic states leads to competing dissociation channels.
• Fragment speed and anisotropy correlate with specific excited states and decay pathways.