Temperature effects in the electronic shells and supershells of lithium clusters

Mass-abundance spectra of isotopically enriched lithium clusters from a gas aggregation source have been recorded for several laser flux densities of the ionizing laser. Shell and supershell structures are clearly observed. Thermal effects are put into evidence which tend to smooth out the shell structure of large masses. At the lowest temperature sharp features are revealed in the node and antinode regions of the beating supershell pattern. These structures are discussed in the light of theoretical models, and compared to other alkalis.