  The systematics of the size dependence of the resonant response of small
metal particles and nuclei to incident electromagnetic radiation is studied.
The known radius$^{-1}$ variation of the full width at half maximum (FWHM) in
matrix-embedded metal particles is qualitatively accounted for by a quantum
calculation of the response within a simple model. In free clusters, the
behaviour is more complicated, possibly because of thermal excitation of
surface modes. For nuclei, the FWHM shows strong shell-structure-linked
oscillations across the periodic table. Focussing on the lower envelope of the
oscillations (magic nuclei), the downward trend of the FWHM is consistent with
the radius$^{-1}$ variation. A schematic theoretical description of the
systematics in nuclei is presented. If the FWHMs are scaled by the respective
Fermi energies and the inverse radii by the Fermi wave vectors, the data sets
for matrix-embedded metal particles and nuclei become comparable in magnitude.
