[en] The ejected-electron spectrum of ytterbium following excitation by electron impact has been measured in the range 0-22.5 eV; 119 spectral features have been tabulated. Excitation was studied over the range of incident electron kinetic energies 8-500 eV. Excitation functions are reported for a number of the autoionising transitions which result in ejected electrons in the range 0-3 eV. (author)