We have fabricated parallel stripes of nanostructures in an n-type Si substrate by implanting 30 keV Ga+ ions from a focused ion beam (FIB) source. Two sets of implantation were carried out. In one case, during implantation the substrate was held at room temperature and in the other case at 400 degrees C. Photoemission electron microscopy (PEEM) was carried out on these samples. The implanted parallel stripes, each with a nominal dimension of 4000 nm x 100 nm, appear as bright regions in the PEEM image. Line scans of the intensities from the PEEM image were recorded along and across these stripes. The intensity pro. le at the edges of a line scan is broader for the implantation carried out at 400 degrees C compared to room temperature. From the analysis of this intensity pro. le, the lateral diffusion coefficient of Ga in silicon was estimated assuming that the PEEM intensity is proportional to Ga concentration. The diffusion coefficient at 400 degrees C has been estimated to be similar to 1.3 x 10 (15) m(2)/s. Across the stripes an asymmetric diffusion pro. le has been observed, which has been related to the sequence of implantation of these stripes and the associated defect distribution due to lateral straggling of the implanted ions. (C) 2009 Elsevier B.V. All rights reserved.