Probing the Transition from van der Waals to Metallic Mercury Clusters

Inner-shell autoionization spectra obtained with synchrotron radiation are reported for mercury clusters ${\mathrm{Hg}}_n$, $n\le 40$. For the small clusters $n\le 12$ 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.