Modified kinetic model of the electron-capture detector - Molecular electron affinities and electron collection modes

The kinetic model for electron-capture detection (ECD) has recently been ex panded to include excited states. Multiple electron affinities for C6F6, an thracene and tetracene have been reported in the literature. The temperatur e dependence of the ECD response is calculated using these values and the e xpanded two state model. Activation energies and pre-exponential terms for kinetic rate constants are determined. The pre-exponential terms for therma l electron attachment are compared with the maximum value calculated from t he DeBroglie wavelength of the electron and the probability for stabilizati on. Temperature data from different methods of electron collection are comp ared. A general procedure for the determination of electron affinities from ECD data is presented. The following ECD electron affinities are reported: C6Cl6, 1.17+/-0.02 and 0.71+/-0.01; C6F5Cl, 0.96+/-0.03 and 0.82+/-0.02; C 6F5NO2, 1.52+/-0.02; C6H5NO2, 1.00+/-0.01 and m-hydroxyacetophenone, 0.74+/ -0.02 (all values in electron volts, eV). (C) 1998 Published by Elsevier Sc ience B.V. All rights reserved.