Abstract
The structure of clean and sodium-covered Si(100)2 x 1 interface is studied theoretically by ab-initio all-electron total-energy calculations (DMol) using very large clusters (up to 77 atoms) and experimentally by polarization-dependent photoemission extended X-ray absorption fine structure (PEXAFS). We have determined the Si-Si dimer bond length and also found that the Si-Si dimer is relaxed upon Na deposition. We find that the Na-Si bond length is equal to the sum of Si and Na covalent radii. We also use the unique ability of PEXAFS to measure the distances between the nearest neighbors of both adsorbate and substrate atoms. The distances obtained for clean Si(100)2 x 1 surface and Na/Si(100)2 x 1 surface from the DMol calculations and PEXAFS experiments are in excellent agreement. Our results allow us to conclude clearly that the Na atom is adsorbed on a single site, the cave, which is also shown to have the lowest adsorption energy.
Original language | English (US) |
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Pages (from-to) | 690-696 |
Number of pages | 7 |
Journal | Applied Surface Science |
Volume | 65-66 |
Issue number | C |
DOIs | |
State | Published - Mar 2 1993 |
Funding
This projectw ass upportedb y the US Office of Naval Research under grant N0004-895-129a0t NorthwesternU niversity,b y the Commissariata I’Energie Atomique (CEA), by the Minis&e de la Recherche et de la Technologie of France (MRT) and by the US National Science Foundation under contract No. DMR LB-07754 at Northern Illinois University. We are grateful to the staff of the Synchrotron Radiation Center of the University of Wisconsin-Madison for their expert technical assistance.
ASJC Scopus subject areas
- General Chemistry
- Condensed Matter Physics
- General Physics and Astronomy
- Surfaces and Interfaces
- Surfaces, Coatings and Films