High-resolution photoabsorption spectrum of jet-cooled propyne

Area of Science:

• Molecular Spectroscopy
• Quantum Chemistry
• Photophysics

Background:

• Propyne's electronic structure and photoabsorption properties are crucial for understanding its behavior in various environments.
• Previous studies have provided limited resolution and assignments for propyne's Rydberg states.

Purpose of the Study:

• To precisely measure the absolute photoabsorption cross section of propyne.
• To investigate and assign Rydberg series, particularly nf series, in the propyne photoabsorption spectrum.
• To analyze spectral structures and vibrational states of the propyne cation.

Main Methods:

• Vacuum-ultraviolet Fourier-transform spectroscopy at Synchrotron Soleil.
• Recording spectra at room temperature (flowing cell) and jet-cooled conditions (~100 K).
• High-resolution spectral analysis (0.9 cm(-1) and 1.8 cm(-1)).

Main Results:

• Detailed absolute photoabsorption cross section of propyne recorded from 62,000 to 88,000 cm(-1).
• New spectral structures observed in jet-cooled spectra, simplifying assignments of Rydberg bands.
• Proposed assignment of a previously unassigned nf Rydberg series.
• Observation of Rydberg series converging to excited vibrational states (v3(+)=1, 2) of the propyne cation.

Conclusions:

• The high-resolution photoabsorption spectrum provides new insights into propyne's electronic transitions and Rydberg structure.
• The study enhances the understanding of molecular ionization processes and vibrational dynamics in cations.
• The findings facilitate more accurate theoretical modeling and interpretation of propyne's spectral features.