Twenty kilovolts massive ion beam system for well-defined microcluster studies

We have constructed a new massive ion beam system for the studies on well-d efined microclusters. The laser-ablation-type cluster source is equipped fo r cluster generation separated from the ionization system. Two types of ion ization systems are prepared: an ArF-excimer laser (193 nm, 0.8 mJ/pulse, 3 ns) or F-2-excimer laser (157 nm, 0.3 mJ/pulse, 3 ns) and an electron impa ct ionizer. The energy and charge state of cluster ions are analyzed with a high accuracy by the sector-type 60 degrees electrostatic analyzer with an orbital radius rho(E) = 200 mm. The size of clusters with a specific energ y and charge state is defined by the 60 degrees magnetic analysis system ch aracterized by an orbital radius rho(M) = 650 mm and the maximum field stre ngth B-max = 1.4 T. The massive ion beam system enables one to provide well mass-selected stable clusters, e.g. Cu-N(q) with sizes ranging as follows N = 1-31 for q = + 1 at energy E = 20 keV, N = 10-63 for q = + 2 at E = 40 keV, N = 44-94 for q = + 3 at E = 60 keV, and N = 121-126 for q = + 4 at E = 80 keV. (C) 1999 Elsevier Science B.V. All rights reserved.