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Measurements of the mass-abundance spectra of sodium clusters from supersonic expansions are presented. The spectra show evidence of a regular spherical shell structure with magic numbers TVo scaling approximately with the cube root of the number of sodium atoms TV, and hence the number of delocalized (valence) electrons in the cluster. Altogether twelve shell closings are observed, adding to the previously known shell closings, TVo = 2, 8, 20, 40, 58, 92, and 138, 260, 344, 440, and 558. The implications of shell structure in such large systems are discussed.

We have used carbon nanotubes to electrically contact a 7 nm gold particle by scanning-probe manipulation. The result was a single-electron transistor showing a periodic modulation of the current as a function of gate voltage for temperatures up to ∼200 K, with the particle responsible for the main features of the electron transport. This interpretation could be verified when the particle was removed and the two nanotubes were moved into electrical contact.

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A sensitive study of the decay of the deformation-aligned # = 14, 4-/is isomer in 174 Hf has revealed a multitude of A>forbidden branches to the ground-state rotational band and other low-A^ bands, in competition with the known decays to high-A' bands. The isomeric transitions have consistently low hindrance factors. These anomalous findings in an axially symmetric deformed nucleus severely test our understanding of the AT-selection rule. The isomeric decay to an 7 = 12 rotation-aligned state, and its mixing with the /"12 yrast state, provide a partial explanation.