36th International Field Emission Symposium
J. Phys. Colloques 50 (1989) C8-91-C8-96
DOI: 10.1051/jphyscol:1989816
EFFECT OF PREADSORBED NICKEL ATOMS UPON THE POTASSIUM MOBILITY ON THE W(112) PLANE
CH. KLEINT1 et R. BLASZCZYSZYN21 Sektion Physik, Karl-Marx-Universität Leipzig, DDR-7010 Leipzig, D.R.G.
2 Institute of Experimental Physics, University of Wroclaw, ul. Cybulskiego 36, PL 50-205 Wroclaw, Poland
Abstract
Spectral density functions W(f) of the field emission flicker noise (FEFN) of a potassium submonolayer ([MATH]k =0.4) adsorbed on a nickel precovered W(112) plane were investigated. An analysis in terms of the Timm and Van der Ziel model was used to determine the K surface diffusion coefficient D. Its dependence on the Ni coverage is presented for a tip temperature of 393 K. With increasing coverage D rises from about 1.6 x 10-9 to 9x10-9 cm2s-1 where the Ni concentration corresponds to the work function maximum of the W(112)Ni system, and then D decreases. The results are consistent with previous FEFN cross-correlation measurements for the same coadsorption system. A smoothing effect caused by the Ni atoms is responsible for the increase of the diffusion coefficient.