Probing the transition from van der Waals to metallic mercury clusters

Inner-shell autoionization spectra obtained with synchrotron radiation are reported for mercury clusters ${\mathrm{Hg}}_{n}$, $n\ensuremath{\le}40$. For the small clusters $n\ensuremath{\le}12$ the spectral behavior as a function of size is interpreted in terms of an excitonic model. For larger cluster sizes a gradual deviation from van der Waals bonding is observed. The asymmetry occuring in the line profiles reflects the progressive construction of the $\mathrm{sp}$ conduction band.