Electron capture in irradiated gases—recent developments

An electron-attachment spectroscopy technique is described which enables the mean energy of electrons to be varied in the range 0.04–0.5 eV by means of a radiofrequency voltage superimposed on the d.c. voltage of an electron-capture detector. Plotting the electron-capture coefficients or the mean electron-capture cross sections against the mean electron energies for each compound yields a characteristic curve which may be helpful for the identification of unknown substances. An increase of the sensitivity and the specificity of the electron-capture detector is also possible. The dependence of the electron-capture coefficient on the mean electron energy for eight substances is discussed.