Triply differential cross sections for electron and positron impact on methane

Area of Science:

• Atomic and Molecular Physics
• Quantum Mechanics
• Chemical Physics

Background:

• Electron and positron impact ionization are fundamental processes in atomic and molecular physics.
• Methane (CH4) is a simple molecule relevant to various chemical and astrophysical environments.
• Understanding ionization dynamics requires accurate theoretical models and experimental validation.

Purpose of the Study:

• To compute theoretical triply differential cross sections (TDCS) for 250 eV electron and positron impact ionization of methane.
• To compare theoretical predictions from different models (DWBA2, M3DW, GSF) with experimental data.
• To investigate the differences in ionization dynamics between electrons and positrons.

Main Methods:

• Calculation of TDCS using the second-order distorted-wave Born approximation (DWBA2).
• Utilizing a non-coplanar geometry for theoretical calculations.
• Comparison of theoretical results with experimental data from Işık et al. (2016) and other theoretical models (M3DW, GSF).

Main Results:

• The DWBA2 theory demonstrated good agreement with experimental results in the low analyzer scattering plane.
• The molecular three body distorted wave (M3DW) approximation also showed agreement, particularly in the perpendicular plane geometry.
• Significant discrepancies were observed between electron and positron TDCS, indicating distinct ionization pathways.

Conclusions:

• The DWBA2 and M3DW theoretical models provide reliable predictions for electron and positron impact ionization of methane.
• The study highlights the importance of choosing appropriate theoretical approximations for accurate ionization cross-section calculations.
• Observed differences in TDCS for electrons and positrons underscore the need for further investigation into their distinct interaction mechanisms.