| AVS 54th International Symposium | |
| Surface Science | Tuesday Sessions |
| Session SS2-TuM |
| Session: | Surface Structure and Growth on Metals |
| Presenter: | M. Shen, Iowa State University |
| Authors: | M. Shen, Iowa State University D.-J. Liu, Ames Laboratory - USDOE, Iowa State University C.J. Jenks, Ames Laboratory - USDOE, Iowa State University J.W. Evans, Ames Laboratory - USDOE, Iowa State University P.A. Thiel, Ames Laboratory - USDOE, Iowa State University |
| Correspondent: | Click to Email |
We have investigated the interaction of sulfur with Ag(111). Sulfur was deposited using an electrochemical evaporator, which generated gas-phase sulfur in the form of S2. Sulfur coverage was measured with Auger electron spectroscopy.1 Images from scanning tunneling microscopy (STM) showed different structures at temperatures between 135 and 300 K. Deposition at 135 K led to the formation of two-dimensional (2D) islands. After heating to 200 K, the surface exhibited a quasi-1D "dot-row" structure, in which each dot was about 0.7 nm in diameter. The dots were aligned in rows that were separated by distances ranging from about 1.6 to 5 nm. Cooling back to 135 K did not restore the initial 2D island structure, indicating that the 2D islands may consist of S2 that dissociates irreversibly in the heating step. At 300 K, no ordered structures were visible, suggesting that the adsorbate becomes very mobile. The STM observations at 300 K and 200 K could be produced reversibly, pointing to a reversible phase transition below room temperature. Development of the dot-row structure at high S coverage was accompanied by pitting on the terraces, indicating participation of Ag. DFT calculations show that Ag3S3 is a candidate for the dots. This complex is analogous to a metal-sulfur complex that has been proposed to exist on Cu(111).2
1 K. Schwaha, N.D. Spencer, R.M. Lambert, Surf. Sci., 81, 273 (1979).
2 P.J. Feibelman, Phys. Rev. Lett., 85, 606 (2000).