Total cross section measurements for electron scattering from dichloromethane.

Area of Science:

• Atomic and Molecular Physics
• Electron Scattering Physics
• Chemical Physics

Background:

• Electron scattering experiments provide crucial data for understanding molecular interactions.
• Dichloromethane (CH2Cl2) is a significant molecule in various chemical processes, necessitating detailed study of its electron interaction properties.
• Previous studies on electron scattering from CH2Cl2 have yielded varying results, highlighting the need for further experimental validation.

Purpose of the Study:

• To accurately measure the total cross sections (TCSs) for electron scattering from dichloromethane (CH2Cl2) over an energy range of 1-300 eV.
• To compare the obtained TCS data with existing experimental and theoretical results for CH2Cl2.
• To investigate the impact of the 'missing angle' effect on measured TCS and identify any shape resonances in the electron scattering process.

Main Methods:

• Utilized a magnetically confined electron transmission apparatus to conduct electron scattering experiments.
• Measured total cross sections (TCSs) for electron scattering from CH2Cl2 across an energy range of 1-300 eV.
• Performed comparative analysis with prior experimental data and theoretical models, including the independent atom model with screening corrected additivity rule and interference term (IAM-SCAR+I).

Main Results:

• The present TCS data for electron scattering from CH2Cl2 show good agreement with Karwasz et al. but poor agreement with Wan et al.
• The 'missing angle' effect was found to significantly influence measured TCS at lower energies, with corrections improving agreement with IAM-SCAR+I+rotations calculations to within 8% above 3 eV.
• Two sigma* (σ*) shape resonances were observed at approximately 2.8 eV and 4.4 eV, consistent with previous electron transmission spectroscopy findings.

Conclusions:

• The study provides reliable TCS data for electron scattering from CH2Cl2, contributing to a better understanding of electron-molecule interactions.
• Accounting for experimental artifacts like the 'missing angle' effect is crucial for accurate comparisons between experimental and theoretical electron scattering data.
• The identification of shape resonances offers insights into the low-energy electron dynamics and potential resonance states in dichloromethane.