Atomic versus molecular Auger decay in CH₂Cl₂ and CD₂Cl₂ molecules.

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Spectroscopy

Background:

• Autoionization processes are crucial for understanding molecular electronic structure and dynamics.
• Chlorine 2p excitation provides a specific probe for studying electronic transitions in halogenated molecules.
• Dichloromethane (CH2Cl2) is a relevant molecule for studying dissociation mechanisms.

Purpose of the Study:

• To analyze the autoionization spectra of CH2Cl2 and its deuterated analog (CD2Cl2) following Cl 2p excitation.
• To assign molecular and atomic Auger transitions and investigate the effect of deuteration.
• To computationally support the ultrafast dissociation mechanism in dichloromethane.

Main Methods:

• Experimental study of autoionization spectra using Cl 2p excitation.
• Assignment of molecular and atomic Auger transitions.
• High-level ab initio quantum mechanical calculations (MCSCF, MRCI).
• Calculation of minimum energy pathways for dissociation, including spin-orbit splitting.

Main Results:

• Observed and assigned distinct molecular and atomic Auger transitions in CH2Cl2 and CD2Cl2.
• Found a reduced contribution of atomic Auger transitions in the deuterated molecule (CD2Cl2).
• Computational results support the presence of an ultrafast dissociation mechanism in dichloromethane.

Conclusions:

• Deuteration influences the contribution of atomic Auger transitions in dichloromethane.
• The study provides strong evidence for ultrafast dissociation pathways in dichloromethane.
• Combined experimental and theoretical approaches offer detailed insights into molecular decay processes.