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

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