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 i ndium surface by normally incident similar to 4 keV Ar+ ions using las er post-ionization in combination with time-of-flight mass spectrometr y. Data on In, clusters represent the largest and heaviest sputtered n eutral cluster for which kinetic energy distribution data are availabl e. 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 measur ed 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 unimol ecular fragmentation on the kinetic energy distributions was investiga ted and found not to significantly affect the measurements.