Studies on GeF₄ Valence and Rydberg States by Electron Impact Spectroscopy and Ab Initio Calculations

Area of Science:

• Quantum Chemistry
• Spectroscopy
• Materials Science

Background:

• Germanium tetrafluoride (GeF4) is a molecule with limited spectroscopic data.
• Understanding its electronic structure is crucial for various chemical applications.

Purpose of the Study:

• To conduct the first comprehensive investigation of singlet and triplet excited electronic states of GeF4.
• To identify and assign low-lying excited states, valence states, Rydberg states, and Rydberg series.
• To support experimental findings with quantum chemical calculations.

Main Methods:

• Electron energy loss (EEL) spectroscopy was employed with incident electrons at 100 eV (5° scattering) and 30 eV (30° scattering).
• Energy loss spectra were measured over the 7.0-18.0 eV range.
• Quantum chemical ab initio calculations were performed to support state assignments.

Main Results:

• Detailed EEL spectra of GeF4 were obtained, revealing low-lying excited states.
• Assignments for triplet, singlet, valence, and Rydberg states were proposed.
• Rydberg series converging to ionization limits were identified based on quantum defect values.
• This work presents the first complete study of GeF4's excited electronic states up to its first ionization energy.

Conclusions:

• The study successfully characterized the excited electronic states of GeF4.
• Experimental EEL spectra and theoretical calculations provide a robust understanding of GeF4's electronic transitions.
• The findings establish a foundation for further research into the photophysics and photochemistry of GeF4.