Quantitative AES and LEED Study of Alkali Metal Overlayers on W(100)

Experimental Auger calibration curves have been obtained for Cs, Rb, K, and Na adsorbed on a W(100) substrate, by monitoring the ratio of the adsorbate-substrate Auger peak-to-peak heights with coverage. A comparative study is made on such curves obtained in the four-grid LEED system and the cylindrical mirror analyzer. The adsorbate on a W substrate has an enhanced Auger yield over that on a Mo substrate due to the increase in the backscattering factor. The attenuation of the substrate Auger electrons is dependent on the atomic number of the alkali adsorbates. The first well-defined LEED pattern during the alkali adsorption revealed a $\mathrm{C}\text{(2×2)}$ structure. At higher coverages a two-domain hcp structure was observed with no change in the $\mathrm{C}\text{(2×2)}$ structure.