200x200nm 2 showing nucleation on a mixed height Pb island (top). Modeling

1. Dynamics of adatoms and nanostructure formationMichael C. Tringides, Iowa State University, DMR 0308595 Nanoscale phenomena can be very different from the ones in the bulk. They are important for Nanotechnology and our ability to control nanostructure nucleation. Nucleation is shown to depend dramatically on island height ( than its chemical nature). A Pb island grown over a step has mixed height ( 5 and 4 layers). On the 5-layer part few fractal islands nucleate and on the 4 layer part many small islands nucleate. Modeling shows dramatically different critical size cluster on the two parts. The origin of this effect is the different quantization of the confined electrons in the two parts. 200x200nm2 showing nucleation on a mixed height Pb island (top). Modeling reproduces the result (bottom). .

2. Dynamics of adatoms and nanostructure formationMichael C. Tringides, Iowa State University, DMR 0308595 The work is a collaboration between the experimental group in Ames and the theoretical group in Prague. The collaboration activities include research, education and outreach.The experiments were carried out in the STM facility in Ames ( top) and involve graduate students ( S. Binz, M. Yakes, J. Chen). The modeling was carried out in Prague ( by PhD student and now staff Z. Kuntova and Dr. Z. Chvoj). Nucleation movies were posted in a public site for outreach http://pub.iglu.cz/PbSi/. Non-technical talks were presented at the two institutions. The picture (bottom) shows (from left to right) the PI, Kuntova, and an undergraduate in Prague during discussions.