Partial Ionization Cross Sections of Tungsten Hexafluoride Due to Electron Impact

Abstract

The ionization data of a neutral molecule are crucial to model the energy deposition and dissociative ionization process. We study theoretically the electron impact ionization process and report on the dissociative ionization cross sections of the tungsten hexafluoride cations invoking the modified-binary-encounter-Bethe model. In this model, the binary-encounter-Bethe model is modified by applying the transformation to the binding energies of the molecular orbitals and then normalizing the partial ionization cross sections of the cations using the branching ratios. The normalization is performed at a particular energy and ensures that the branching ratios of different fragments are summed to unity. The model yielded satisfactory results for both the singly and doubly ionized ions. The approach validates the results of Basner et al. The advantages and limitations of this model are also discussed. This work corroborates the importance of mass spectrometry data in the proper understanding of the ionization process.

Keywords

• mass spectrometry
• cations
• appearance energy
• branching ratio
• plasma modeling
• electron ionization