Fission of multiply charged alkaline earth metal clusters

We have studied the fission of multiply photoionized alkaline earth metal clusters having charges up to Z = +5 by means of high-resolution time-of-flight mass spectrometry. The determined appearance sizes can be compared to results of simple model calculations assuming that both fragments can still be treated as metallic liquid droplets. In this case the measured appearance sizes for the alkaline earth metals are found to be smaller than the ones predicted by the calculations. However, if one fixes the small fragment to be an atomic ion, good agreement between measurement and theory is acheived.     

Optical response of cesium coated C60

Photoabsorption spectra are reported for Cs _n ⁺ and C₆₀Cs_n ⁺ + clusters for n=40, 60, 120 and 310. The spectra were obtained by heating the mass selected clusters in a beam by means of photoabsorption until they evaporated metal atoms. The resulting mass loss was observed in a time-of-flight mass spectometer. The plasmon-like resonance in pure Cs clusters shifts to lower energies with decreasing cluster size. The collective electronic excitations in clusters containing C₆₀ are split in energy as would be expected for fullerene molecules coated with layers of metal.     

Transition metal coated fullerenes

Compound clusters of fullerene molecules and transition metal atoms having the composition C₆₀M_x and C₇₀M_x with x = 0..150 and M ∈ {Ti, Zr, V, Y, Ta, Nb} were produced using laser vaporisation in a low-pressure inert gas aggregation cell. Intensity anomalies in the mass spectra correlate with the atomic radii of the different metals indicating the formation of complete metal layers around the central fullerene molecule. Using high laser intensities the metal-fullerene clusters can be transformed into metcars and metal-carbides. Photofragmentation spectra of preselected C₆₀Ta_x indicate that the fullerene cage is destroyed for x ≥ 3.