AVS 56th International Symposium & Exhibition
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM11
Sulfur Adsorption on Ag(111) and Ag(100): Structures and Surface Dynamics

Wednesday, November 11, 2009, 11:20 am, Room N

Session: Surface Chemistry and Dynamics
Presenter: D.-J. Liu, Iowa State University
Authors: D.-J. Liu, Iowa State University
M. Shen, Iowa State University
S. Russel, Iowa State University
C.J. Jenks, Iowa State University
J.W. Evans, Iowa State University
P.A. Thiel, Iowa State University
Correspondent: Click to Email
Exposure to sulfur (S) of Ag(111) and Ag(100) produces ordered surface structures as observed by STM. On Ag(111), a self-organized dot-row structure forms at around 200 K [1]. The dots, likely Ag3S3 clusters, can rearrange and form other more closed-packed structures at higher S coverages. On Ag(100) at 230 K, a √17 reconstruction structure appears for S coverage above 0.25 ML, together with a p(2x2) structure. STM studies also reveal that exposure to sulfur generally accelerates coarsening of 2D Ag nanoislands preformed on the surface by Ag deposition. For Ag(111), since steps serve as sinks for S, dramatic enhancement of Ostwald ripening only occurs above a threshold (step saturation) coverage of S [2]. For Ag(100), Ostwald ripening is activated with a rate increasing gradually with increasing S coverage. Possible acceleration mechanisms include AgnSm complex mediated mass transport, or S-catalyzed attachment-detachment. We perform a detailed analysis of the stability and formation energies of various structures and Ag-S complexes using DFT. Many aspects of the observed structures and mechanisms for mass transport during coarsening are elucidated based on these DFT energetics together with kinetic modeling.

[1] Shen et al. J. Phys. Chem. C 112 (2008) 4281

[2] Shen et al. J. Chem. Phys. 130 (2009) 094701