ELECTRON-IMPACT EXCITATION OF THE 3P-3 STATE IN MAGNESIUM

A modulated crossed beam technique has been used to measure the differential cross sections for the excitation of the 33P state in magnesium by electrons at impact energies of 10 and 20 eV. The cross sections are measured over a range of scattering angles from 10 to 130-degrees. Our results agree with the previous experimental cross sections of Williams and Trajmar within the combined uncertainties, however the present data reduce the uncertainty by almost an order of magnitude thereby allowing a meaningful comparison to be made with the predictions of the various theories. At this time no theory accurately predicts the behaviour of the cross sections over the whole angular range.