Electron and Positron Scattering Cross Sections from CO₂: A Comparative Study over a Broad Energy Range (0.1-5000...

Area of Science:

• Atomic and Molecular Physics
• Scattering Theory
• Quantum Mechanics

Background:

• Understanding electron and positron scattering cross sections is crucial for various applications, including plasma physics and radiation chemistry.
• Previous studies have provided compilations of scattering data, but experimental and theoretical inconsistencies remain, particularly for positron scattering.

Purpose of the Study:

• To conduct a comprehensive comparative study of electron and positron scattering cross sections from CO2 molecules across a wide energy range (0.1-5000 eV).
• To provide updated and self-consistent sets of integral cross sections for elastic and inelastic scattering channels for both electrons and positrons.
• To investigate the discrepancies between theoretical predictions, such as the first Born approximation, and experimental observations for positron scattering.

Main Methods:

• Experimental measurement of total electron scattering cross sections (e-TCS) using a high-resolution electron beam transmission system.
• Analysis of dissociative electron attachment processes by measuring O- anion production yields.
• Theoretical calculations using the Independent Atom Model with Screening Corrected Additive Rule (IAM-SCARI) for elastic, inelastic, and total scattering cross sections.
• Development of self-consistent integral cross section datasets by referencing existing compilations and new measurements/calculations.

Main Results:

• New e-TCS measurements for electron scattering from 1 to 200 eV.
• Calculations revealed significant differences in electron and positron scattering behavior, including target polarization effects and excitation efficiencies.
• Positron scattering cross sections were found to be lower at higher energies, contradicting charge independence predictions of the first Born approximation.
• Self-consistent integral cross section datasets for both electron and positron scattering, covering elastic, vibrational, electronic, ionization, and positronium formation channels, were generated.
• Derived data for direct ionization and positronium formation in positron scattering showed excellent agreement with experimental results.

Conclusions:

• Electron and positron scattering from CO2 exhibit distinct energy-dependent behaviors, with notable deviations from charge independence predictions.
• The study provides valuable, self-consistent cross-section data crucial for advancing theoretical models and applications.
• Inconsistencies in current theoretical models necessitate further development of sophisticated computational methods for accurate scattering process descriptions.