Electron affinity evaluation for nitrobenzene derivatives using negative ion lifetime data.

Adiabatic Electron Affinity (EAa) is one of the fundamental properties of a molecule. EA values can be measured with various experimental methods, although their availability is still relatively limited. Here we extend our evaluations of EAas using Negative Ion Mass Spectrometry (NIMS). A series of eleven nitrobenzene derivatives were investigated by means of NIMS. The mean autodetachment lifetimes of molecular anions were measured. Vertical and adiabatic EAs were also estimated using DFT calculations. For the compounds under investigation, the EAas evaluated from the measured anion lifetimes, assuming a simple Arrhenius approximation, are in good agreement with the corresponding experimental values. It is shown that the pre-exponential frequency factor (typical time of the anion motion on the reaction coordinate) is of the order of magnitude of 500 fs.