KrF excimer laser ablation of iron disilicide in the alpha phase (alpha-FeSi2) has been investigated using time-of-flight (TOF) mass spectroscopy to characterize the dependence of ejected neutrals and native positive ions on laser fluence. The TOF mass-spectra,a showed that the ejection behavior was classified into three parts at low, moderate and high fluence ranges. At laser fluences below 0.7 j/cm(2), the presence of only Si, Fe and Si-2 neutrals was confirmed; the arrival profile of Si atoms is well described by a Maxwell-Boltzmann (MB) distribution with a translational velocity of 1.6 x 10(3) m/s corresponding to a kinetic energy of 0.35 eV, and a target surface temperature of 4.0 x 10(3) K, indicating a thermal emission of these neutral species. With increasing the fluence, nascent positive ions, such as singly- or doubly-charged Si and Fe ions appeared; the arrival profiles of these ions are observed to fit a shifted MB distribution. Their kinetic energies range from several eV at moderate fluences to over 100 eV at high fluences up to 2.5 J/cm(2). These high kinetic energies cannot be explained in terms of the FeSi2 target surface reaching a temperature that would produce such energetic ions upon ablation, suggesting the ion acceleration in a dense plasma plume. (C) 2002 Elsevier Science B.V. All rights reserved.