Electronic excited-state mixing in NeCl2.

Area of Science:

• Physical Chemistry
• Quantum Chemistry
• Spectroscopy

Background:

• Understanding electronic energy transfer in van der Waals complexes like NeCl2 is crucial for molecular dynamics.
• Previous models did not fully account for spin-orbit interactions in the NeCl2 system.
• The B electronic state of chlorine molecules is known to be involved in energy transfer processes.

Purpose of the Study:

• To investigate the electronic states of the NeCl2 system using ab initio calculations.
• To explore the role of spin-orbit interactions in the electronic energy transfer mechanism.
• To propose a new mechanism for electronic energy transfer from excited chlorine molecules.

Main Methods:

• Performed ab initio calculations explicitly including spin-orbit interactions for NeCl2 electronic states.
• Analyzed the potential energy surfaces and geometric dependencies of electronic state interactions.
• Investigated the transition between direct coupling and intramolecular vibrational relaxation regimes.

Main Results:

• Observed a surprising curve crossing for the C2v, T-shaped geometry in the NeCl2 system.
• Demonstrated state mixing away from the C2v geometry, as anticipated.
• Identified a novel mechanism for electronic energy transfer involving the Ne atom and excited Cl2.

Conclusions:

• The Ne atom's role in energy transfer is geometry-dependent, particularly during intramolecular vibrational relaxation.
• The proposed mechanism highlights the coupling of Cl2 B3Pi0u+ with a 3Pi2g state via the Ne atom.
• These findings provide new insights into the dynamics of electronic energy transfer in NeCl2.