Width of the plasmon resonance in metal clusters

The width of the plasmon resonance in the clusters ${\mathrm{Na}}_9^{+}$, ${\mathrm{Na}}_{21}^{+}$, and ${\mathrm{Na}}_{41}^{+}$ is investigated in the framework of the structure-averaged jellium model and compared with recent experimental data. The two leading mechanisms for the line broadening are fragmentation of the resonance into nearby 1ph states and splitting through thermal quadrupole fluctuations. The fragmentation becomes activated mainly through octupole fluctuations and it gives the dominating contribution to the width.