Sputtering yields and Specific energy losses of Ar+Ions with energies from 5 TO 30 KeV AT SiO2

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Abstract
Sputtering yields are determined from interference micrographs of the etched pits developing during ablation of discharged silica surfaces by a homogeneous Ar ion beam at normal incidence. The maximum of the sputtering yield was found to be 1.8 atoms per incident ion at about 20 keV. The bombardment of thin silica layers on a glass substrate results in photoemission of sputtered target particles and ionoluminescence; specific energy losses are evaluated from the time-varying spectrd and intensity distributions which can be observed during sputtering. Both these specific energy losses and those calculated from sputtering yields are compared with the results from the unified sputtering theory of Brandt and Laubert predicting proportionality of the sputtering yield and the specific energy losses. The experimentally determined energy losses show the same energy dependence among each other and are more energy dependent than the theoretical results. If the surface is not discharged during ablation, then the sputtering yields increase up to 75%; however, the energy losses evaluated from the distribution of luminescenceand photoemission do not increase by more than 25%, this indicates a change of the momentum distribution within the collision cascade due to an attractive force between negative-charged oxygen ions and the positive-charged surface of the target.