R-matrix benchmark study of SO2 photoionization dynamics

Area of Science:

• Atmospheric Chemistry
• Astrochemistry
• Quantum Mechanics

Background:

• Sulfur dioxide (SO2) is vital in atmospheric and astronomical contexts, influencing greenhouse warming and ozone chemistry.
• It is frequently observed in planetary atmospheres and interstellar environments.
• SO2 participates in sulfur plasma and shock-driven chemical processes.

Purpose of the Study:

• To investigate the photoionization dynamics of sulfur dioxide using advanced computational methods.
• To calculate total and state-resolved cross sections for the primary ionic states of SO2.
• To provide benchmark data for atmospheric and interstellar modeling.

Main Methods:

• Employed the ab initio R-matrix method with close-coupling approximation.
• Calculated photoionization cross sections for the three lowest ionic states of SO2.
• Benchmarked computed cross sections against available experimental data.

Main Results:

• Revealed significant autoionizing resonances in the near-threshold photoionization spectrum of SO2.
• Presented the first direct state-resolved theoretical cross sections for dominant photoionization channels.
• Established that the lowest three ionic states (X2A1, A2B2, B2A2) exclusively form the parent SO2+ ion.

Conclusions:

• The computed cross sections are robust and reliable, validated through systematic benchmarks.
• This study offers critical reference data for photochemical and radiative process modeling in various environments.
• Sulfur dioxide serves as an important benchmark system for molecular photoionization research.