KINETIC-ENERGY DISTRIBUTIONS OF SPUTTERED INDIUM ATOMS AND CLUSTERS

The kinetic energy distributions of neutral indium atoms and clusters through In, were measured during the sputtering of a polycrystalline indium surface by normally incident similar to 4 keV Ar+ ions using laser post-ionization in combination with time-of-flight mass spectrometry. Data on In, clusters represent the largest and heaviest sputtered neutral cluster for which kinetic energy distribution data are available. The slopes of the high energy tails for the various cluster kinetic energy distributions are nearly equal to each other and to the values found for copper and aluminum cluster distributions previously measured in this laboratory. The energies at which the distributions reach a maximum decrease from a value of 1.6 eV for In atoms to a value of 1.1 eV for In-g. The possible influence of photofragmentation and unimolecular fragmentation on the kinetic energy distributions was investigated and found not to significantly affect the measurements.