Electronic structure and spectroscopy of oxyallyl: a theoretical study

Area of Science:

• Quantum chemistry
• Theoretical spectroscopy
• Chemical physics

Background:

• The electronic structure of the oxyallyl diradical and its anion is crucial for understanding their reactivity and spectral properties.
• Previous studies have provided limited theoretical insights into the low-lying electronic states and photodetachment spectra.

Purpose of the Study:

• To investigate the electronic structure of the oxyallyl diradical and anion using high-level ab initio methods.
• To calculate energy differences between electronic states and anion detachment energies.
• To elucidate the origins of experimentally observed spectral features.

Main Methods:

• High-level ab initio electronic structure calculations.
• Two-dimensional potential energy surface scans for singlet oxyallyl.
• Reduced-dimensionality wave packet dynamics calculations.
• Photodetachment spectrum simulations.

Main Results:

• Adiabatic energy differences between the anion (2)A(2) and neutral (3)B(2) and (3)B(1) states were estimated at 1.94 and 2.73 eV.
• Singlet oxyallyl (1)A(1) lacks a diradical minimum, undergoing prompt barrierless ring closure.
• Resonance trapping in the Franck-Condon region explains spectral line broadening (approx. 200 cm(-1)) due to wave packet persistence (~170 fs).

Conclusions:

• The theoretical findings strongly support the experimental assignment of the oxyallyl anion photoelectron spectrum.
• The study clarifies the electronic structure and dynamics governing the observed spectral characteristics.
• High-level ab initio methods are effective for characterizing transient chemical species like oxyallyl.