Optically Forbidden Excitations of 3s Electron of Argon by Fast Electron Impact

The electron energy loss spectrum of argon in the energy region of 24.5-30.5 eV was measured at 2.5 keV impact energy. The line profile parameters of the optically forbidden excitations of 3s^-1 ns (n = 4-6) and 3s^-1 nd (n = 3-7) of argon, i.e., E_γ, Γ, q and μ, were determined.