Fast-electron-impact study on excitations of 4d electron of xenon

The electron energy loss spectrum of the 4d excitations of xenon was measured at an incident electron energy of 1500 eV and a scattering angle of 6°. Besides the optically allowed transitions of 4d_5/2^-1np and 4d_3/2^-1np', the optically forbidden transitions of 4_5/2^-1ns, 4d_5/2^-1nd, 4d_3/2^-1ns', and 4d_3/2^-1nd' were observed. The measured features are assigned with the help of the calculation by the Cowan Code. The line profile parameters of both optically allowed transitions and optically forbidden ones were determined and compared with the previous available data. It is found that the natural widths of both dipole-allowed and dipole-forbidden excitations are approximately identical, which means the spectator transitions dominate the resonant Auger effect for both dipole-allowed and dipole-forbidden transitions.