DETERMINATION OF THE ELECTRON-AFFINITIES OF MOLECULES USING NEGATIVE-ION MASS-SPECTROMETRY

The electron affinities of sulfur hexafluoride, nitrobenzene, two chloroethylenes, and hexafluorobenzene have been obtained by analyzing the temperature dependence of thermal electron attachment negative ion mass spectra. The electron affinities are as follows: SF6, 1.07 +/- 0.07 eV; C6H5NO2, 1.0 +/- 0.06 eV; C6F6, 0.83 +/- 0.2 eV; C2Cl4, 0.64 +/- 0.03 eV; C2HCl3, 0.40 +/- 0.22 eV. The values support the literature values for SF6 and C6H5NO2 and the chloroethylenes. On the basis of these results, an experimental procedure for measuring molecular electron affinities is presented.