ONSET OF INTERSTITIAL DIFFUSION DETERMINED BY SCANNING-TUNNELING-MICROSCOPY

A new method using variable temperature scanning tunneling microscopy (STM) to determine the onset temperature of the diffusion of self-inte rstitial atoms is presented. The interstitials are produced by a low f luence of Ne+ (4.5 keV) bombardment of Pt(111) at 20 K. At 22 K, the i nterstitials become mobile and migrate to the surface where they pop o ut and can be detected as new adatoms by STM. The time dependence of t he appearance of the interstitials at the surface is measured for two temperatures, allowing estimation of the diffusion parameters.