Structural Properties of Clusters

We study the stability and the structure of metal ion-doped noble gas clusters M+Xn (M=metal atom and X=noble gas atom) using time-of-flight (TOF) mass spectrometry. By changing systematically the composition M/X, we observe changes in the “magic” numbers patterns in the TOF-spectra according to the clusters structures and structural transitions.


A) Metal ions with spherical orbitals

All the recorded spectra exhibit magic numbers, which change gradually from the familiar icosahedral sequence N=n+1=13,19,23,26,29,32,.. to another series of magic numbers N=9,10,11,17,21,24, 26,27,30,.. as the atomic size ratio of the metal ion to the noble gas atom decreases. Furthermore, as the cluster size increases, the new sequence seems to convert again to the icosahedral one at a critical cluster size. A simple hard sphere packing model is developed and molecular dynamics simulations using pairwise additive Lennard-Jones potentials are performed in order to explain the structural transition as a function of cluster size.



Text Box: Intensity  µ Stability

B) Metal ions with non-spherical orbitals

In this case the morphology of the atomic orbital (e.g. d-orbital) defines the structure and the stability of the system. To this end Crystal Field theory and also Density functional calculations have been performed to explain the observed stability and to deduce the structure of the corresponding clusters.