Studies of neutral AlmCn clusters employing a table-top soft x-ray laser

Neutral Al m C n clusters are investigated both experimentally and theoretically for the first time. Single photon ionization through 193 nm, and 46.9 nm lasers is used to detected neutral cluster distributions. Al m C n clusters are generated through laser ablation of a mixture of Al and C powders pressed into a disk. An oscillation of the VIEs of Al m C n clusters is observed in the experiments. The ionization energies of Al m C n clusters change as a function of the numbers of Al and C atoms in the clusters. Theoretical density functional theory and ab initio calculations are carried out to explore the structures, ionization energies, and molecular orbitals of the Al m C n clusters. C=C bonds are favored for the lowest energy structures for Al m C n clusters. Based on calculations of HOMOs (highest occupied molecular orbitals) of Al m C n clusters we find that the ionization energies of these clusters do not simply depend on open or closed shell valence electron configurations, but also depend on the electronic structure details of the clusters. The calculational results provide good and consistent explanations of the experimental observations, and are consistent with them.