Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms vol:193 pages:787-793
The internal energy distribution of neutral indium clusters In-n, sputtered from a polycrystalline In surface by 15 keV Xe+ ions is investigated by means of laser post-ionization and time-of-flight mass spectrometry. In particular, the neutral species are ionized by a tunable frequency doubled dye-laser and the photoionization efficiency (PIE) curves were collected with the photon energy varied around the ionization potential. This way, internal energy distributions of sputtered clusters in the size range n = 2-35 could be determined using photon energies of 4.2-6 eV. The results are compared with the PIE curves of cold indium clusters which were produced by a supersonic nozzle expansion using a laser vaporization source and investigated under otherwise similar conditions. As a result, the sputtered clusters show a distinctive broadening of the PIE curve in the threshold region, thus illustrating the influence of the sputtering process in increasing the internal energy of the ejected clusters. (C) 2002 Elsevier Science B.V. All rights reserved.