Photodissociation dynamics of phenol

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Photochemistry

Background:

• Phenol photodissociation is crucial for understanding aromatic compound fragmentation.
• Previous studies lacked detailed insights into energy partitioning and reaction channels.

Purpose of the Study:

• To elucidate the photodissociation mechanisms of phenol at 193 and 248 nm.
• To characterize the energy distribution of photofragments, particularly carbon monoxide (CO).
• To correlate experimental findings with theoretical calculations.

Main Methods:

• Multimass ion-imaging techniques for fragment trajectory analysis.
• Step-scan time-resolved Fourier-transform spectroscopy for spectral detection.
• Quantum chemical calculations and RRKM theory for theoretical support.

Main Results:

• Identified OH bond cleavage, CO, and H2O elimination as major channels at 193 nm; OH and CO elimination at 248 nm.
• Determined translational energy distributions indicating H-atom elimination from excited and ground states, while CO/H2O elimination occurs from the ground state.
• Characterized nascent carbon monoxide (CO) product with high rotational (approx. 4600 K) and vibrational (3350 K) temperatures, and specific energy distributions.

Conclusions:

• Experimental results align with theoretical potential energy surfaces and RRKM calculations.
• Detailed understanding of phenol's photochemical pathways and energy disposal was achieved.
• Provides a foundation for further studies on aromatic molecule photodissociation.