Autoionization Emission from Transition Metals by Electron Impact

Intense gain satellites associated with the $M_{2,3}\mathrm{VV}$ Auger transition have been observed for representative $3d$ transition metals. The satellites have line shapes and intensities that resemble those of the $M_{2,3}$ electron-energy-loss and resonant photon-excited spectra of these materials and are identified as being due to autoionization electron emission. This identification satisfies the expectation that the Fano effect should be manifest in both absorption and emission experiments, whether photon or electron excited.