### Abstract

This paper describes a modified additivity rule for the calculation of electron impact ionization cross-sections of molecules and radicals of the form AB_{n}(n = 1-6). This additivity rule incorporates weighting factors for the contributions to the molecular ionization cross-sections from the ionization cross-sections of the constituent atoms, which depend explicitly on the atomic radii and the effective number of atomic electrons. In a few special cases (hydrides where the other constituent atom has a radius smaller than the radius of the H atom and species where both constituent atoms have radii smaller than the radius of the H atom), the weighting factors can be simplified, so that they depend only on the atomic radii, i.e. on geometric effects. A comprehensive comparison of the predictions of this new modified additivity rule with available experimental data and with other theoretical predictions is presented.

Original language | English (US) |
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Pages (from-to) | 503-517 |

Number of pages | 15 |

Journal | International Journal of Mass Spectrometry and Ion Processes |

Volume | 167-168 |

State | Published - Dec 1 1997 |

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### Keywords

- Additivity rule
- Cross sections
- Electron ionization
- Molecules

### ASJC Scopus subject areas

- Spectroscopy

### Cite this

_{n}.

*International Journal of Mass Spectrometry and Ion Processes*,

*167-168*, 503-517.