Electron collisions with X(CH₃)₄ molecules (X = C, Si, Ge)

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Cross Section Measurements

Background:

• Electron scattering studies are crucial for understanding molecular interactions.
• Permethylated compounds offer unique insights into molecular structure effects on scattering.
• Previous studies have explored electron scattering from simpler hydrides.

Purpose of the Study:

• To measure absolute total cross sections (TCSs) for electron scattering from C(CH3)4, Si(CH3)4, and Ge(CH3)4.
• To investigate the influence of permethylation on electron scattering dynamics.
• To analyze resonant scattering processes in these molecules.

Main Methods:

• Absolute grand-total cross sections were measured using a linear electron-transmission experiment.
• Electron-impact energies ranged from approximately 0.5 to 300 eV.
• Integral elastic cross sections (ECS) and ionization cross sections (ICS) were calculated using model methods.

Main Results:

• Pronounced broad enhancements in TCS were observed, peaking around 5.5 eV for Si(CH3)4 and Ge(CH3)4, and 6.5 eV for C(CH3)4.
• Weak structures were identified at higher electron energies, attributed to resonant scattering processes.
• The sum of calculated ECS and ICS generally agreed with measured TCS above 50 eV.

Conclusions:

• Resonant processes play a significant role in electron scattering from tetramethylmethane, tetramethylsilane, and tetramethylgermane.
• Permethylation influences the observed scattering features, particularly the energy dependence of TCS.
• Calculated ECS+ICS provide a reliable estimation for TCS at energies above 300 eV.