Threshold photoelectron spectroscopy of ozone

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Quantum Chemistry

Background:

• Ozone (O3) is a crucial molecule in atmospheric chemistry.
• Understanding its electronic structure and ionization processes is vital for atmospheric modeling.
• Previous spectroscopic studies lacked the resolution to fully elucidate ozone's ionic states and vibrational complexities.

Purpose of the Study:

• To obtain the first high-resolution threshold photoelectron spectrum of ozone.
• To determine precise ionization energies of ozone's electronic states.
• To interpret the observed spectral features, including vibrational structures and indirect ionization processes.

Main Methods:

• Utilized synchrotron radiation for excitation.
• Acquired threshold photoelectron spectra in the 12-21 eV energy range.
• Achieved a spectral resolution of 21-38 meV.

Main Results:

• Presented the first high-resolution threshold photoelectron spectrum of ozone.
• Identified and assigned the first three ionic states (1 2A1, 1 2B2, 1 2A2).
• Observed enhanced band intensities above 16 eV due to indirect ionization processes, not seen in conventional photoelectron spectroscopy.
• Resolved extensive vibrational structures, revealing irregular spacing in the 2 2B1 band.

Conclusions:

• The high-resolution spectrum provides unprecedented detail on ozone's electronic and vibrational states.
• Indirect ionization processes significantly contribute to spectral features above 16 eV.
• The findings offer a more comprehensive understanding of ozone's ionic states and dynamics.