Abstract
Scanning tunneling microscopy studies reveal that trace amounts of adsorbed S below a critical coverage on the order of 10 mML have little effect on the coarsening and decay of monolayer Ag adatom islands on Ag(111) at 300 K. In contrast, above this critical coverage, decay is greatly accelerated. This critical value appears to be determined by whether all S can be accommodated at step edges. Accelerated coarsening derives from the feature that the excess S (above that incorporated at steps) produces significant populations on the terraces of metal-sulfur complexes, which are stabilized by strong Ag-S bonding. These include Ag S2, Ag2 S2, Ag2 S3, and Ag3 S3. Such complexes are sufficiently populous and mobile that they can potentially lead to greatly enhanced metal mass transport across the surface. This picture is supported by density functional theory analysis of the relevant energetics, as well as by reaction-diffusion equation modeling to assess the mechanism and degree of enhanced coarsening.
Original language | English |
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Article number | 094701 |
Journal | Journal of Chemical Physics |
Volume | 130 |
Issue number | 9 |
DOIs | |
State | Published - 2009 |
Externally published | Yes |
Funding
We thank Karina Morgenstern for information on previous studies of Ag adatom island decay on S-free Ag(111). This work was supported by NSF Grant No. CHE-0809472. D.J.L. was supported by the Division of Chemical Sciences, BES, U.S. Department of Energy (U.S. DOE). This work was performed at Ames Laboratory, which is operated for the U.S. DOE by Iowa State University under Contract No. DE-AC02-07CH11358.
Funders | Funder number |
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Division of Chemical Sciences | |
National Science Foundation | 0809472 |
U.S. Department of Energy | |
Basic Energy Sciences | |
Iowa State University |