On the Competition Between Electron Autodetachment and Dissociation of Molecular Anions

Gerd Marowsky,Albert A Viggiano,Jürgen Troe

doi:10.1007/s13361-019-02237-z

Abstract

We treat the competition between autodetachment of electrons and unimolecular dissociation of excited molecular anions as a rigid-/loose-activated complex multichannel reaction system. To start, the temperature and pressure dependences under thermal excitation conditions are represented in terms of falloff curves of separated single-channel processes within the framework of unimolecular reaction kinetics. Channel couplings, caused by collisional energy transfer and “rotational channel switching” due to angular momentum effects, are introduced afterward. The importance of angular momentum considerations is stressed in addition to the usual energy treatment. Non-thermal excitation conditions, such as typical for chemical activation and complex-forming bimolecular reactions, are considered as well. The dynamics of excited SF6− anions serves as the principal example. Other anions such as CF3− and POCl3− are also discussed.

Highlights

Excited molecular anions may undergo a variety of processes such as dissociation to anionic and neutral fragments, autodetachment of electrons, radiative stabilization, and collisional deactivation
The foregoing section provided falloff curves for separated electron detachment and dissociation of thermally excited SF6−. It illustrated that electron detachment in the language of Bkinetic modeling^ effectively proceeds as a rigid-activated complex (AC) process whereas dissociation is a loose-AC process
Dissociative electron attachment (DEA) experiments start with non-thermal distributions of the states of the anions

Summary

Introduction

Excited molecular anions may undergo a variety of processes such as dissociation to anionic and neutral fragments, autodetachment of electrons, radiative stabilization, and collisional deactivation (or activation). Falloff Curves for Separated Electron Detachment and Dissociation Processes of SF6− They include the factor exp[−ΔE0/kBT] where ΔE0 corresponds to the energy difference between SF6 + e− and SF5− + F at 0 K (being 0.41 eV [7]).

Results

Conclusion