Photoelectron spectra of SinC−m cluster anions (1≤n≤7 and 1≤m≤5) were measured at the photon energies of 3.49 eV, by using a magnetic bottle electron spectrometer. The SinC−m clusters were produced either by a laser vaporization of a silicon–carbon mixed rod or by two laser vaporizations of carbon and silicon rods in a He carrier gas. The spectra of the SinC−1 (3≤n≤7) clusters are similar to those of pure Si−n+1 clusters in the peak positions and their envelopes, which is attributed to the isovalent electronic structure of Si and C atoms as well as to the similar geometrical structure. In contrast, the similarity in the photoelectron spectra is not observed between C−m+1 and Si1C−m (2≤m≤5) clusters, which is attributed to a change in their geometry; from chain to ring. These experimental conclusions are discussed with the results of our theoretical calculations.

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Indium-sodium (In,Na,) bimetallic clusters were produced by two independent laser vaporization methods.Ionization potentials (IPS) of the In,Nam clusters were measured up to m = 2 using a tunable ultraviolet laser combined with a time-of-flight (TOF) mass spectrometer. At small sizes (n = 3-1 5 ) , the ionization potentials decrease by 0.1-0.8 eV with the addition of N a atom@), whereas the IPS of larger In, (15 I n I 27) clusters do not decrease with N a addition. Moreover, IPS of In7Nal and In13Nal clusters are higher than those of In7 and Inl3, and the IP increments can be explained by electronic shell closings of the l p (8e) and 2p shell (40 e), where In atoms in the clusters are monovalent and trivalent, respectively. The electronic shell structure was also examined by a magic number in mass distributions of In,Na,-cluster anions; the In12Na3-cluster can be observed as magic numbers, corresponding to the 2p shell closing. In contrast, no electronic shell structure is observed in pure In, clusters around n = 13. These results indicate that Na atom addition can induce s / p hybridization in the In, clusters. W e also present mass distributions of aluminum-sodium cluster anions, Al,Na,-, whose feature can be understood by the electronic shell model.

Photoelectron spectra of AlnS−1 (1≤n≤9) cluster anions were measured at the photon energies of 3.49 and 4.66 eV, using a magnetic bottle electron spectrometer having ∼60 meV resolution. AlS− has an electron affinity of as large as 2.6 eV, attributed to large stability by six bonding electrons. A new electronic state, A′ 2Π, was found 0.4 eV above the AlS ground state, which is in agreement with theoretical calculations. AlnS−1 cluster anions are produced efficiently up to n=5, but the production of larger cluster sizes is found difficult. The mass distribution of AlnS−1 cluster anions and electron binding energy can be explained by a geometric structure obtained by theoretical calculation.