The effect of surface recoils on the energy distribution of sputtered gold

Modifications have been made to the time-of-flight spectrometer enabling energy analysis of sputtered gold atoms with recoil angles of theta=560-1400. Preliminary results using polycrystalline gold show the effect of direct and deflected surface recoils on the energy distribution of sputtered atoms. In the region of theta<900 a high energy peak appears in the time-of-flight distribution. As theta decreases from 900 this peak shifts to higher energies an amount expected for direct surface recoils. For theta>900, which is the region where only deflected surface recoils are expected, a high energy peak does not appear. However, the random collision cascade peak does show a skewness towards higher energies which decreases as theta increases from 900. At theta=1350 the distribution has a Esup(-1.8) dependence which is close to that expected for random collision cascades. The next stage of the work is to determine to what extent focusing collisions, as opposed to surface collisions, contribute to the <100> and <110> sputtered spots in gold. (Auth.)